







 
   
     
       
         Horological disquisitions concerning the nature of time, and the reasons why all days, from noon to noon, are not alike twenty four hours long in which appears the impossibility of a clock's being always kept exactly true to the sun : with tables of equation, and newer and better rules ... how thereby precisely to adjust royal pendulums ... : with a table of pendulums, shewing the beats that any length makes in an hour ... / by John Smith ... ; to which is added The best rules for the ordering and use both of the quick-silver and spirit weather-glasses, and Mr. S. Watson's rules for adjusting a clock by the fixed stars.
         Smith, John, fl. 1673-1680.
      
       
         
           1694
        
      
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             Horological disquisitions concerning the nature of time, and the reasons why all days, from noon to noon, are not alike twenty four hours long in which appears the impossibility of a clock's being always kept exactly true to the sun : with tables of equation, and newer and better rules ... how thereby precisely to adjust royal pendulums ... : with a table of pendulums, shewing the beats that any length makes in an hour ... / by John Smith ... ; to which is added The best rules for the ordering and use both of the quick-silver and spirit weather-glasses, and Mr. S. Watson's rules for adjusting a clock by the fixed stars.
             Smith, John, fl. 1673-1680.
          
           [4], 92 p.
           
             Printed for Richard Cumberland ...,
             London :
             1694.
          
           
             Includes one folded table of equations.
             "Licensed, January 17, 1693/4, D. Poplar"--P. 2.
             Reproduction of original in British Library.
          
        
      
    
     
       
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         eng
      
       
         
           Time, Equation of -- Early works to 1800.
           Horology -- Early works to 1800.
        
      
    
     
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             Horological
             Disquisitions
          
           Concerning
           the
           NATURE
           of
           TIME
           ,
           AND
           THE
           Reasons
           why
           all
           Days
           ,
           from
           Noon
           to
           Noon
           ,
           are
           not
           alike
           Twenty
           Four
           Hours
           long
           .
           In
           which
           appears
           the
           Impossibility
           of
           a
           Clock's
           being
           always
           kept
           exactly
           true
           to
           the
           Sun.
           With
           TABLES
           of
           EQUATION
           ,
           and
           Newer
           and
           Better
           RULES
           than
           any
           yet
           extant
           ,
           how
           thereby
           precisely
           to
           adjust
           ROYAL
           PENDULUMS
           ,
           and
           keep
           them
           afterwards
           ,
           as
           near
           as
           possible
           to
           the
           apparent
           Time.
           With
           a
           TABLE
           of
           PENDULUMS
           ,
           shewing
           the
           BEATS
           that
           any
           Length
           makes
           in
           an
           Hour
           .
           A
           Work
           very
           necessay
           for
           all
           that
           would
           understand
           the
           true
           way
           of
           rightly
           managing
           Clocks
           and
           Watches
           .
        
         
           By
           
             JOHN
             SMITH
          
           ,
           C.
           M.
           
        
         
           To
           which
           is
           added
           ,
           The
           best
           Rules
           for
           the
           Ordering
           and
           Use
           both
           of
           the
           Quick-Silver
           and
           
             Spirit
             Weather-Glasses
          
           :
           And
           Mr.
           S.
           Watson's
           Rules
           for
           adjusting
           a
           Clock
           by
           the
           
             Fixed
             Stars
          
           .
        
         
           LONDON
           :
           Printed
           for
           
             Richard
             Cumberland
          
           at
           the
           Angel
           in
           S.
           Paul
           '
           
             s
             Church-Yard
          
           .
           1694.
           
        
      
       
         
         
           Licensed
           ,
        
         
           
             
               January
               17.
               1693
               
               /
               4.
               
            
          
           
             D.
             Poplar
             .
          
        
      
       
         
         
           TO
           THE
           READER
           .
        
         
           THE
           Design
           of
           these
           Papers
           is
           not
           to
           cover
           the
           Clock-Makers
           Imperfections
           ,
           as
           some
           have
           suggested
           ,
           but
           plainly
           to
           demonstrate
           thetrue
           Reason
           of
           those
           unavoidable
           Variations
           between
           the
           Time
           given
           by
           the
           Sun
           and
           that
           of
           a
           good
           and
           well-adjusted
           Clock
           ;
           and
           to
           give
           such
           Directions
           as
           may
           yet
           reduce
           them
           to
           a
           nearer
           Agreement
           in
           Time
           :
           In
           doing
           of
           which
           I
           have
           endeavoured
           to
           express
           my self
           in
           such
           Words
           as
           I
           thought
           most
           proper
           to
           inform
           the
           Reader
           's
           Understanding
           .
           What
           is
           here
           exposed
           to
           publick
           View
           is
           not
           the
           Result
           of
           mere
           Speculation
           ,
           but
           of
           Skill
           and
           Practice
           ,
           
           for
           as
           it
           has
           been
           my
           Profession
           ,
           so
           it
           has
           been
           my
           Care
           and
           Concern
           also
           to
           understand
           exactly
           not
           only
           the
           Nature
           of
           a
           Clock
           ,
           but
           that
           also
           of
           its
           Motion
           ,
           and
           the
           Result
           of
           my
           Discoveries
           :
           As
           to
           the
           latter
           ,
           you
           have
           very
           briefly
           laid
           down
           in
           the
           following
           Discourse
           ;
           and
           I
           assure
           you
           that
           I
           have
           not
           spoken
           any
           thing
           of
           the
           Truth
           of
           which
           I
           was
           not
           first
           well
           satisfied
           .
        
         
           The
           Style
           indeed
           is
           purely
           Mechanick
           ,
           but
           this
           is
           no
           Argument
           against
           its
           usefulness
           ,
           since
           in
           Books
           Men
           ought
           not
           so
           much
           to
           heed
           who
           't
           is
           that
           speaks
           as
           what
           is
           spoken
           .
           He
           always
           writes
           best
           that
           from
           his
           own
           Knowledge
           and
           Experience
           can
           inform
           the
           World
           of
           something
           that
           's
           advantagious
           to
           Human
           Life
           ,
           which
           was
           not
           known
           to
           Mankind
           in
           the
           Times
           before
           .
        
         
           Farewel
           .
        
         
      
       
         
         
           A
           Table
           of
           Equations
           ,
           Shewing
           the
           true
           Length
           of
           every
           Natural-Day
           ,
           or
           the
           Seconds
           of
           Time
           that
           they
           are
           either
           Longer
           or
           shorter
           than
           XXIV
           .
           Hours
           .
        
         
           By
           JOHN
           SMITH
           C.
           M.
           
        
         
           
             
               
                  
              
               
                 Jan.
                 
              
               
                 Feb.
                 
              
               
                 Mar.
                 
              
               
                 April
              
               
                 May
              
               
                 June
              
               
                 July
              
               
                 Aug.
                 
              
               
                 Sept.
                 
              
               
                 Octo.
                 
              
               
                 Nov.
                 
              
               
                 Dec.
                 
              
            
             
               
                  
              
               
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                 24
              
               
                  
              
               
                 24
              
               
                  
              
               
                 30
              
            
             
               
                 23
              
               
                  
              
               
                 8
              
               
                  
              
               
                 15
              
               
                  
              
               
                 19
              
               
                  
              
               
                 7
              
               
                  
              
               
                 9
              
               
                  
              
               
                 10
              
               
                  
              
               
                 4
              
               
                  
              
               
                 19
              
               
                  
              
               
                 19
              
               
                 D
              
               
                 24
              
               
                  
              
               
                 25
              
               
                  
              
               
                 30
              
            
             
               
                 24
              
               
                  
              
               
                 ●
              
               
                  
              
               
                 15
              
               
                  
              
               
                 19
              
               
                  
              
               
                 7
              
               
                  
              
               
                 10
              
               
                  
              
               
                 10
              
               
                  
              
               
                 5
              
               
                  
              
               
                 19
              
               
                  
              
               
                 18
              
               
                  
              
               
                 1
              
               
                  
              
               
                 25
              
               
                  
              
               
                 30
              
            
             
               
                 25
              
               
                  
              
               
                 5
              
               
                  
              
               
                 15
              
               
                  
              
               
                 19
              
               
                  
              
               
                 6
              
               
                  
              
               
                 10
              
               
                  
              
               
                 10
              
               
                  
              
               
                 5
              
               
                  
              
               
                 19
              
               
                  
              
               
                 17
              
               
                  
              
               
                 2
              
               
                  
              
               
                 25
              
               
                  
              
               
                 28
              
            
             
               
                 26
              
               
                  
              
               
                 4
              
               
                  
              
               
                 15
              
               
                  
              
               
                 19
              
               
                  
              
               
                 5
              
               
                  
              
               
                 11
              
               
                  
              
               
                 10
              
               
                  
              
               
                 5
              
               
                  
              
               
                 20
              
               
                  
              
               
                 17
              
               
                  
              
               
                 2
              
               
                  
              
               
                 25
              
               
                  
              
               
                 23
              
            
             
               
                 29
              
               
                  
              
               
                 ●
              
               
                  
              
               
                 16
              
               
                  
              
               
                 19
              
               
                  
              
               
                 5
              
               
                  
              
               
                 11
              
               
                  
              
               
                 10
              
               
                  
              
               
                 5
              
               
                  
              
               
                 20
              
               
                  
              
               
                 16
              
               
                  
              
               
                 3
              
               
                  
              
               
                 26
              
               
                  
              
               
                 23
              
            
             
               
                 28
              
               
                  
              
               
                 ●
              
               
                  
              
               
                 17
              
               
                  
              
               
                 19
              
               
                  
              
               
                 5
              
               
                  
              
               
                 11
              
               
                  
              
               
                 9
              
               
                  
              
               
                 6
              
               
                  
              
               
                 20
              
               
                  
              
               
                 16
              
               
                  
              
               
                 4
              
               
                  
              
               
                 26
              
               
                  
              
               
                 27
              
            
             
               
                 29
              
               
                  
              
               
                 ●
              
               
                  
              
               
                  
              
               
                  
              
               
                 18
              
               
                  
              
               
                 4
              
               
                  
              
               
                 11
              
               
                  
              
               
                 9
              
               
                  
              
               
                 7
              
               
                  
              
               
                 20
              
               
                  
              
               
                 16
              
               
                  
              
               
                 6
              
               
                  
              
               
                 27
              
               
                  
              
               
                 27
              
            
             
               
                 30
              
               
                  
              
               
                 1
              
               
                  
              
               
                  
              
               
                  
              
               
                 17
              
               
                  
              
               
                 4
              
               
                  
              
               
                 11
              
               
                  
              
               
                 8
              
               
                  
              
               
                 8
              
               
                  
              
               
                 20
              
               
                  
              
               
                 15
              
               
                  
              
               
                 7
              
               
                  
              
               
                 28
              
               
                  
              
               
                 25
              
            
             
               
                 31
              
               
                 D
              
               
                 24
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                 9
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                  
              
               
                 8
              
               
                  
              
               
                  
              
               
                  
              
               
                 24
              
            
          
        
         
           The
           Character
           D
           24
           ,
           shews
           what
           Days
           are
           truly
           24
           Hours
           long
           ,
           the
           
             Red
             Figures
          
           shew
           the
           
             Seconds
             of
             Time
          
           ,
           that
           those
           Days
           on
           which
           they
           are
           plac'd
           are
           longer
           than
           24
           Hours
           ,
           and
           the
           
             Black
             Ones
          
           shew
           how
           many
           Seconds
           those
           Days
           are
           shorter
           than
           24
           Hours
           :
           And
           here
           you
           are
           to
           note
           ,
           That
           in
           those
           parts
           of
           the
           Year
           where
           days
           are
           above
           24
           Hours
           long
           ,
           there
           a
           well
           adjusted
           Clock
           will
           gain
           ,
           because
           the
           Pendulum-Day
           ,
           which
           is
           the
           24
           Hours
           ,
           of
           its
           own
           Motion
           will
           be
           finish'd
           before
           the
           Natural-Day
           is
           ended
           .
           On
           the
           contrary
           ,
           Where
           the
           Days
           are
           less
           in
           length
           than
           24
           Hours
           ,
           there
           the
           Clock
           will
           lose
           ,
           or
           go
           too
           slow
           ,
           because
           the
           Pendulum-Day
           will
           not
           be
           ended
           so
           soon
           as
           the
           Natural
           one
           .
        
         
           London
           :
           Printed
           for
           R.
           Cumberland
           ,
           at
           the
           Angel
           in
           S.
           Paul's
           Church-Yard
           .
        
      
       
         
         
           A
           Second
           Table
           of
           Equations
           ,
           Shewing
           how
           to
           order
           a
           well-adjusted
           Clock
           ,
           so
           as
           that
           the
           whole
           Year
           round
           it
           shall
           not
           differ
           above
           the
           Sixteenth
           Part
           of
           an
           Hour
           from
           the
           Sun
           ,
           or
           3′
           45″
           .
        
         
           By
           JOHN
           SMITH
           .
           C.
           M.
           
        
         
           
             
               
                  
              
               
                 Jan.
                 
              
               
                 Feb.
                 
              
               
                 Mar.
                 
              
               
                 Apr.
                 
              
               
                 May
              
               
                 June
              
               
                 July
              
               
                 Aug.
                 
              
               
                 Sept.
                 
              
               
                 Octo.
                 
              
               
                 Nov.
                 
              
               
                 Dec.
                 
              
            
             
               
                  
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
               
                 ′
              
               
                 ″
              
            
             
               
                 1
              
               
                 7
                 ♁
              
               
                 8
              
               
                 2
              
               
                 49
              
               
                 1
              
               
                 40
              
               
                 3
              
               
                 28
              
               
                 1
              
               
                 48
              
               
                  
              
               
                 59
              
               
                 1
              
               
                 34
              
               
                 1
              
               
                 28
              
               
                  
              
               
                 20
              
               
                 2
              
               
                 5
              
               
                  
              
               
                 34
              
               
                 2
              
               
                 43
              
            
             
               
                 2
              
               
                 3
              
               
                 21
              
               
                 2
              
               
                 49
              
               
                 1
              
               
                 57
              
               
                 3
              
               
                 11
              
               
                 1
              
               
                 51
              
               
                 1
              
               
                 00
              
               
                 1
              
               
                 41
              
               
                 1
              
               
                 19
              
               
                  
              
               
                 00
              
               
                 2
              
               
                 19
              
               
                  
              
               
                 43
              
               
                 3
              
               
                 12
              
            
             
               
                 3
              
               
                 2
              
               
                 58
              
               
                 2
              
               
                 47
              
               
                 2
              
               
                 14
              
               
                 2
              
               
                 55
              
               
                 1
              
               
                 54
              
               
                 1
              
               
                 11
              
               
                 1
              
               
                 48
              
               
                 1
              
               
                 10
              
               
                  
              
               
                 20
              
               
                 2
              
               
                 33
              
               
                  
              
               
                 53
              
               
                 7
                 ♁
              
               
                 28
              
            
             
               
                 4
              
               
                 2
              
               
                 35
              
               
                 2
              
               
                 45
              
               
                 2
              
               
                 32
              
               
                 2
              
               
                 39
              
               
                 1
              
               
                 55
              
               
                 5
                 ♁
              
               
                 8
              
               
                 1
              
               
                 55
              
               
                 1
              
               
                 1
              
               
                  
              
               
                 41
              
               
                 2
              
               
                 46
              
               
                 1
              
               
                 3
              
               
                 3
              
               
                 15
              
            
             
               
                 5
              
               
                 2
              
               
                 13
              
               
                 2
              
               
                 41
              
               
                 2
              
               
                 50
              
               
                 2
              
               
                 24
              
               
                 1
              
               
                 55
              
               
                 3
              
               
                 33
              
               
                 2
              
               
                 1
              
               
                  
              
               
                 50
              
               
                 1
              
               
                 2
              
               
                 2
              
               
                 59
              
               
                 1
              
               
                 13
              
               
                 2
              
               
                 45
              
            
             
               
                 6
              
               
                 1
              
               
                 52
              
               
                 2
              
               
                 37
              
               
                 3
              
               
                 8
              
               
                 2
              
               
                 9
              
               
                 1
              
               
                 55
              
               
                 3
              
               
                 11
              
               
                 2
              
               
                 7
              
               
                  
              
               
                 38
              
               
                 1
              
               
                 23
              
               
                 3
              
               
                 12
              
               
                 1
              
               
                 24
              
               
                 2
              
               
                 15
              
            
             
               
                 7
              
               
                 1
              
               
                 32
              
               
                 2
              
               
                 33
              
               
                 3
              
               
                 26
              
               
                 1
              
               
                 55
              
               
                 1
              
               
                 54
              
               
                 2
              
               
                 58
              
               
                 2
              
               
                 13
              
               
                  
              
               
                 25
              
               
                 1
              
               
                 44
              
               
                 3
              
               
                 25
              
               
                 1
              
               
                 36
              
               
                 1
              
               
                 45
              
            
             
               
                 8
              
               
                 1
              
               
                 13
              
               
                 2
              
               
                 28
              
               
                 7
                 ♁
              
               
                 29
              
               
                 1
              
               
                 41
              
               
                 1
              
               
                 52
              
               
                 2
              
               
                 45
              
               
                 2
              
               
                 19
              
               
                  
              
               
                 12
              
               
                 2
              
               
                 6
              
               
                 5
                 ♁
              
               
                 10
              
               
                 1
              
               
                 48
              
               
                 1
              
               
                 15
              
            
             
               
                 9
              
               
                  
              
               
                 55
              
               
                 2
              
               
                 23
              
               
                 3
              
               
                 27
              
               
                 1
              
               
                 27
              
               
                 1
              
               
                 50
              
               
                 2
              
               
                 32
              
               
                 2
              
               
                 24
              
               
                  
              
               
                 2
              
               
                 2
              
               
                 28
              
               
                 1
              
               
                 11
              
               
                 2
              
               
                 1
              
               
                  
              
               
                 45
              
            
             
               
                 10
              
               
                  
              
               
                 38
              
               
                 2
              
               
                 17
              
               
                 3
              
               
                 9
              
               
                 1
              
               
                 13
              
               
                 1
              
               
                 47
              
               
                 2
              
               
                 19
              
               
                 2
              
               
                 28
              
               
                  
              
               
                 16
              
               
                 2
              
               
                 50
              
               
                 1
              
               
                 1
              
               
                 2
              
               
                 16
              
               
                  
              
               
                 15
              
            
             
               
                 11
              
               
                  
              
               
                 22
              
               
                 2
              
               
                 9
              
               
                 2
              
               
                 51
              
               
                 1
              
               
                 0
              
               
                 1
              
               
                 44
              
               
                 2
              
               
                 6
              
               
                 2
              
               
                 32
              
               
                  
              
               
                 31
              
               
                 3
              
               
                 11
              
               
                  
              
               
                 52
              
               
                 2
              
               
                 33
              
               
                  
              
               
                 15
              
            
             
               
                 12
              
               
                  
              
               
                 6
              
               
                 2
              
               
                 1
              
               
                 2
              
               
                 33
              
               
                  
              
               
                 47
              
               
                 1
              
               
                 41
              
               
                 1
              
               
                 53
              
               
                 2
              
               
                 35
              
               
                  
              
               
                 46
              
               
                 7
                 ♁
              
               
                 17
              
               
                  
              
               
                 44
              
               
                 2
              
               
                 50
              
               
                  
              
               
                 45
              
            
             
               
                 13
              
               
                  
              
               
                 10
              
               
                 1
              
               
                 52
              
               
                 2
              
               
                 15
              
               
                  
              
               
                 35
              
               
                 1
              
               
                 37
              
               
                 1
              
               
                 40
              
               
                 2
              
               
                 37
              
               
                 1
              
               
                 1
              
               
                 3
              
               
                 25
              
               
                  
              
               
                 37
              
               
                 3
              
               
                 8
              
               
                 1
              
               
                 15
              
            
             
               
                 14
              
               
                  
              
               
                 26
              
               
                 1
              
               
                 43
              
               
                 1
              
               
                 56
              
               
                  
              
               
                 28
              
               
                 1
              
               
                 33
              
               
                 1
              
               
                 27
              
               
                 2
              
               
                 39
              
               
                 1
              
               
                 17
              
               
                 3
              
               
                 5
              
               
                  
              
               
                 30
              
               
                 3
              
               
                 26
              
               
                 1
              
               
                 45
              
            
             
               
                 15
              
               
                  
              
               
                 42
              
               
                 1
              
               
                 33
              
               
                 1
              
               
                 37
              
               
                  
              
               
                 12
              
               
                 1
              
               
                 28
              
               
                 1
              
               
                 14
              
               
                 ●
              
               
                 40
              
               
                 1
              
               
                 33
              
               
                 2
              
               
                 45
              
               
                  
              
               
                 24
              
               
                 7
                 ♁
              
               
                 20
              
               
                 2
              
               
                 16
              
            
             
               
                 16
              
               
                  
              
               
                 57
              
               
                 1
              
               
                 23
              
               
                 1
              
               
                 1
                 17
              
               
                  
              
               
                 1
              
               
                 1
              
               
                 23
              
               
                 1
              
               
                 1
              
               
                 2
              
               
                 40
              
               
                 1
              
               
                 50
              
               
                 2
              
               
                 25
              
               
                  
              
               
                 18
              
               
                 3
              
               
                 25
              
               
                 2
              
               
                 47
              
            
             
               
                 17
              
               
                 1
              
               
                 1
              
               
                 1
              
               
                 12
              
               
                  
              
               
                 57
              
               
                  
              
               
                 9
              
               
                 1
              
               
                 17
              
               
                  
              
               
                 49
              
               
                 2
              
               
                 40
              
               
                 2
              
               
                 7
              
               
                 2
              
               
                 5
              
               
                  
              
               
                 13
              
               
                 3
              
               
                 4
              
               
                 7
                 ♁
              
               
                 3
              
            
             
               
                 18
              
               
                 1
              
               
                 24
              
               
                 1
              
               
                 00
              
               
                  
              
               
                 37
              
               
                  
              
               
                 19
              
               
                 1
              
               
                 11
              
               
                  
              
               
                 37
              
               
                 2
              
               
                 39
              
               
                 2
              
               
                 24
              
               
                 1
              
               
                 45
              
               
                  
              
               
                 9
              
               
                 2
              
               
                 42
              
               
                 3
              
               
                 14
              
            
             
               
                 19
              
               
                 1
              
               
                 36
              
               
                  
              
               
                 47
              
               
                  
              
               
                 17
              
               
                  
              
               
                 29
              
               
                 1
              
               
                 5
              
               
                  
              
               
                 26
              
               
                 2
              
               
                 37
              
               
                 2
              
               
                 42
              
               
                 1
              
               
                 25
              
               
                  
              
               
                 6
              
               
                 2
              
               
                 19
              
               
                 2
              
               
                 44
              
            
             
               
                 20
              
               
                 1
              
               
                 47
              
               
                  
              
               
                 34
              
               
                  
              
               
                 3
              
               
                  
              
               
                 39
              
               
                  
              
               
                 59
              
               
                  
              
               
                 15
              
               
                 2
              
               
                 34
              
               
                 3
              
               
                 00
              
               
                 1
              
               
                 9
              
               
                  
              
               
                 3
              
               
                 1
              
               
                 56
              
               
                 2
              
               
                 14
              
            
             
               
                 21
              
               
                 1
              
               
                 58
              
               
                  
              
               
                 21
              
               
                  
              
               
                 22
              
               
                  
              
               
                 49
              
               
                  
              
               
                 52
              
               
                  
              
               
                 4
              
               
                 2
              
               
                 30
              
               
                 3
              
               
                 19
              
               
                  
              
               
                 47
              
               
                  
              
               
                 1
              
               
                 1
              
               
                 32
              
               
                 1
              
               
                 44
              
            
             
               
                 22
              
               
                 2
              
               
                 8
              
               
                  
              
               
                 7
              
               
                  
              
               
                 41
              
               
                  
              
               
                 58
              
               
                  
              
               
                 44
              
               
                  
              
               
                 7
              
               
                 2
              
               
                 26
              
               
                 7
                 ♁
              
               
                 23
              
               
                  
              
               
                 28
              
               
                  
              
               
                 1
              
               
                 1
              
               
                 8
              
               
                 1
              
               
                 14
              
            
             
               
                 23
              
               
                 2
              
               
                 17
              
               
                  
              
               
                 7
              
               
                 1
              
               
                 00
              
               
                 1
              
               
                 5
              
               
                  
              
               
                 36
              
               
                  
              
               
                 18
              
               
                 2
              
               
                 22
              
               
                 3
              
               
                 26
              
               
                  
              
               
                 9
              
               
                  
              
               
                 1
              
               
                  
              
               
                 44
              
               
                  
              
               
                 44
              
            
             
               
                 24
              
               
                 2
              
               
                 25
              
               
                  
              
               
                 22
              
               
                 1
              
               
                 19
              
               
                 1
              
               
                 12
              
               
                  
              
               
                 27
              
               
                  
              
               
                 28
              
               
                 2
              
               
                 18
              
               
                 3
              
               
                 7
              
               
                  
              
               
                 10
              
               
                  
              
               
                 1
              
               
                  
              
               
                 19
              
               
                  
              
               
                 14
              
            
             
               
                 25
              
               
                 2
              
               
                 31
              
               
                  
              
               
                 37
              
               
                 1
              
               
                 38
              
               
                 1
              
               
                 19
              
               
                  
              
               
                 17
              
               
                  
              
               
                 38
              
               
                 2
              
               
                 13
              
               
                 2
              
               
                 48
              
               
                  
              
               
                 28
              
               
                  
              
               
                  
              
               
                  
              
               
                 6
              
               
                  
              
               
                 16
              
            
             
               
                 26
              
               
                 2
              
               
                 36
              
               
                  
              
               
                 52
              
               
                 1
              
               
                 57
              
               
                 1
              
               
                 25
              
               
                  
              
               
                 7
              
               
                  
              
               
                 48
              
               
                 2
              
               
                 8
              
               
                 2
              
               
                 29
              
               
                  
              
               
                 45
              
               
                  
              
               
                 4
              
               
                  
              
               
                 31
              
               
                  
              
               
                 41
              
            
             
               
                 27
              
               
                 2
              
               
                 40
              
               
                 1
              
               
                 7
              
               
                 2
              
               
                 16
              
               
                 1
              
               
                 30
              
               
                  
              
               
                 4
              
               
                  
              
               
                 38
              
               
                 2
              
               
                 3
              
               
                 2
              
               
                 9
              
               
                 1
              
               
                 2
              
               
                  
              
               
                 6
              
               
                  
              
               
                 56
              
               
                 1
              
               
                 12
              
            
             
               
                 28
              
               
                 2
              
               
                 43
              
               
                 1
              
               
                 23
              
               
                 2
              
               
                 35
              
               
                 1
              
               
                 35
              
               
                  
              
               
                 16
              
               
                 1
              
               
                 8
              
               
                 1
              
               
                 58
              
               
                 1
              
               
                 44
              
               
                 1
              
               
                 18
              
               
                  
              
               
                 9
              
               
                 1
              
               
                 22
              
               
                 1
              
               
                 40
              
            
             
               
                 29
              
               
                 2
              
               
                 46
              
               
                  
              
               
                  
              
               
                 2
              
               
                 54
              
               
                 1
              
               
                 40
              
               
                  
              
               
                 26
              
               
                 1
              
               
                 17
              
               
                 1
              
               
                 52
              
               
                 1
              
               
                 29
              
               
                 1
              
               
                 34
              
               
                  
              
               
                 13
              
               
                 1
              
               
                 48
              
               
                 2
              
               
                 7
              
            
             
               
                 30
              
               
                 2
              
               
                 48
              
               
                  
              
               
                  
              
               
                 3
              
               
                 13
              
               
                 1
              
               
                 44
              
               
                  
              
               
                 37
              
               
                 1
              
               
                 26
              
               
                 1
              
               
                 45
              
               
                 1
              
               
                 00
              
               
                 1
              
               
                 50
              
               
                  
              
               
                 19
              
               
                 2
              
               
                 15
              
               
                 2
              
               
                 34
              
            
             
               
                 31
              
               
                 2
              
               
                 49
              
               
                  
              
               
                  
              
               
                 7
                 ♁
              
               
                 16
              
               
                  
              
               
                  
              
               
                  
              
               
                 48
              
               
                  
              
               
                  
              
               
                 1
              
               
                 37
              
               
                  
              
               
                 40
              
               
                  
              
               
                  
              
               
                  
              
               
                 26
              
               
                  
              
               
                  
              
               
                 2
              
               
                 59
              
            
          
        
         
           Note
           ,
           the
           Day
           on
           which
           this
           Mark
           ♁
           is
           plac'd
           ,
           are
           
             Rectifying
             Days
          
           ;
           on
           any
           Day
           then
           that
           is
           not
           a
           Rectifying-Day
           ,
           let
           the
           Clock
           be
           Set
           so
           much
           too
           Slow
           as
           the
           Black
           ,
           or
           so
           much
           too
           Fast
           as
           the
           
             Red
             Figures
          
           express
           ,
           and
           so
           let
           him
           go
           on
           till
           a
           Rectifying-Day
           ,
           on
           which
           let
           Him
           be
           Set
           backward
           if
           the
           Figures
           on
           the
           Rectifying-Day
           are
           Black
           ,
           or
           forward
           if
           the
           Figures
           are
           Red
           ;
           just
           so
           many
           Minutes
           and
           Seconds
           as
           the
           sum
           of
           Figures
           are
           on
           the
           Rectifying-Day
           ,
           and
           continue
           so
           to
           do
           each
           Rectifying-Day
           following
           ;
           and
           then
           the
           Clock
           in
           the
           Intermediate
           Spaces
           between
           will
           agree
           with
           the
           Sun
           ,
           as
           the
           Figures
           in
           the
           Table
           express
           ,
           that
           is
           will
           be
           either
           so
           must
           too
           Fast
           ,
           or
           so
           much
           too
           slow
           .
        
         
           London
           ,
           Printed
           for
           Richard
           Cumberland
           at
           the
           Angel
           in
           S.
           Paul
           '
           
             s
             Church-Yard
          
           ,
           1694.
           
        
      
    
     
       
         
         
         
           of
           use
           no
           longer
           than
           the
           Sun
           shines
           :
           The
           next
           to
           this
           ,
           of
           any
           value
           and
           Esteem
           ,
           was
           that
           of
           the
           Hour-Glass
           ;
           an
           excellent
           Contrivance
           ,
           if
           its
           Usefulness
           at
           all
           Times
           be
           considered
           ;
           but
           the
           Care
           required
           to
           keep
           it
           in
           continual
           Motion
           did
           still
           excite
           the
           Ingenious
           to
           endeavour
           the
           Discovery
           of
           something
           else
           that
           might
           not
           only
           be
           yet
           more
           exact
           ,
           but
           free
           too
           from
           the
           continual
           Toil
           ,
           as
           I
           may
           call
           it
           ,
           and
           Trouble
           of
           Attendance
           .
        
         
           In
           process
           of
           Time
           this
           came
           to
           be
           performed
           in
           part
           ,
           by
           the
           way
           of
           Clock-Work
           ;
           a
           Device
           first
           of
           all
           started
           among
           the
           Germans
           ,
           from
           whom
           the
           Art
           of
           making
           Clocks
           dispersed
           it self
           over
           other
           Parts
           of
           Europe
           ,
           but
           as
           yet
           Defective
           as
           to
           its
           exact
           and
           steady
           keeping
           of
           Time
           :
           At
           length
           ,
           in
           Holland
           ,
           an
           Ingenious
           and
           Learned
           Gentleman
           ,
           Mr.
           
             Christian
             Hugens
          
           ,
           by
           Name
           ,
           found
           out
           the
           Way
           to
           regulate
           the
           uncertainty
           of
           its
           Motion
           by
           the
           Vibration
           of
           a
           Pendulum
           .
        
         
           From
           Holland
           ,
           the
           fame
           of
           this
           Invention
           soon
           past
           over
           into
           England
           ,
           where
           several
           eminent
           and
           ingenious
           Workmen
           applyed
           themselves
           to
           rectify
           
           some
           Defects
           which
           as
           yet
           was
           found
           therein
           ;
           among
           which
           that
           eminent
           and
           well-known
           Artist
           Mr.
           
             William
             Clement
          
           ,
           had
           at
           last
           the
           good
           Fortune
           to
           give
           it
           the
           finishing
           Stroke
           ,
           he
           being
           indeed
           the
           real
           Contriver
           of
           that
           curious
           kind
           of
           long
           Pendulum
           ,
           which
           is
           at
           this
           Day
           so
           universally
           in
           use
           among
           us
           .
        
         
           An
           Invention
           that
           exceeds
           all
           others
           yet
           known
           ,
           as
           to
           the
           Exactness
           and
           Steadiness
           of
           its
           Motion
           ,
           which
           proceeds
           from
           Two
           Properties
           ,
           peculiar
           to
           this
           Pendulum
           :
           The
           one
           is
           the
           weightiness
           of
           its
           Bob
           ,
           and
           the
           other
           the
           little
           Compass
           in
           which
           it
           plays
           :
           The
           first
           of
           these
           makes
           it
           less
           apt
           to
           be
           commanded
           by
           those
           accidental
           differences
           of
           Strength
           that
           may
           sometimes
           happen
           in
           the
           Draught
           of
           the
           Wheels
           ,
           and
           the
           other
           renders
           the
           Vibrations
           more
           equal
           and
           exact
           ,
           as
           not
           being
           capable
           of
           altering
           so
           much
           in
           the
           distance
           of
           its
           Swinge
           ,
           as
           those
           other
           kind
           of
           Pendulums
           are
           ,
           who
           fetch
           a
           larger
           ,
           and
           ,
           by
           consequence
           ,
           a
           less
           constant
           Compass
           .
        
         
         
           For
           Pendulums
           that
           swing
           or
           vibrate
           very
           far
           out
           ,
           as
           all
           Crown-Wheel
           Pendulums
           do
           ,
           are
           apt
           ,
           by
           reason
           of
           many
           Accidents
           that
           happen
           to
           vary
           much
           in
           the
           Distance
           ,
           they
           swing
           ,
           and
           that
           's
           the
           reason
           they
           do
           not
           always
           go
           or
           move
           the
           same
           Pace
           ,
           a
           larger
           Vibration
           taking
           up
           more
           Time
           to
           be
           performed
           in
           ,
           than
           lesser
           ones
           do
           :
           But
           the
           Vibrations
           of
           this
           Pendulum
           of
           Mr.
           
           Clement's
           contrivance
           is
           so
           very
           exact
           and
           steady
           ,
           that
           ,
           when
           't
           is
           well
           in
           Order
           ,
           and
           the
           Air
           of
           the
           same
           Consistence
           ,
           it
           shall
           in
           Five
           hundred
           or
           a
           Thousand
           Revolutions
           of
           its
           Index
           ,
           keep
           so
           equal
           a
           Time
           ,
           that
           no
           Human
           Art
           can
           discover
           the
           least
           considerable
           Difference
           in
           any
           of
           its
           Revolutions
           ,
           an
           excellence
           to
           which
           no
           other
           known
           Motion
           can
           as
           yet
           pretend
           ,
           and
           for
           which
           I
           think
           it
           will
           not
           be
           improper
           now
           ,
           at
           last
           ,
           to
           call
           it
           the
           
             Royal
             Pendulum
          
           .
        
         
           But
           although
           the
           Motion
           thereof
           be
           so
           very
           curiously
           exact
           and
           equal
           ,
           yet
           't
           will
           not
           for
           all
           that
           regulate
           the
           Motion
           of
           a
           Clock
           in
           such
           a
           manner
           as
           that
           the
           Index
           or
           Hand
           shall
           continually
           agree
           with
           that
           Time
           which
           the
           Sun
           gives
           ;
           
           for
           by
           constant
           Experience
           we
           find
           ,
           that
           the
           best
           of
           Clocks
           ,
           when
           exactly
           adjusted
           ,
           will
           yet
           be
           found
           in
           some
           considerable
           Time
           of
           going
           to
           be
           either
           too
           fast
           or
           too
           flow
           for
           the
           Sun
           ,
           although
           it
           was
           at
           the
           first
           set
           right
           therewith
           .
        
         
           Now
           this
           Disagreement
           cannot
           be
           occasioned
           by
           any
           Defect
           proper
           to
           the
           Motion
           of
           the
           Pendulum
           ,
           each
           Twenty
           Four
           Hours
           ;
           of
           which
           ,
           when
           well
           rectified
           ,
           being
           the
           same
           for
           length
           of
           Time
           ,
           but
           it
           does
           proceed
           from
           an
           irregularity
           in
           the
           Sun
           's
           apparent
           Motion
           ,
           which
           does
           occasion
           great
           diversity
           in
           the
           Lengths
           of
           Natural
           Days
           .
           'T
           is
           generally
           believed
           indeed
           that
           the
           natural
           Day
           ,
           or
           the
           Time
           between
           12.
           and
           12.
           a
           Clock
           ,
           is
           always
           in
           length
           just
           24.
           
           Hours
           :
           But
           this
           is
           a
           great
           Mistake
           ,
           for
           it
           will
           appear
           by
           the
           following
           Accounts
           of
           it
           ,
           that
           it
           is
           but
           in
           some
           Parts
           of
           the
           Year
           that
           the
           Days
           are
           so
           ;
           in
           all
           the
           other
           Parts
           ,
           between
           these
           ,
           they
           are
           found
           continually
           to
           differ
           ,
           being
           sometimes
           above
           24.
           
           Hours
           long
           ,
           and
           sometimes
           less
           than
           24.
           
           Hours
           ;
           and
           though
           the
           Differences
           may
           seem
           but
           a
           small
           matter
           to
           some
           ,
           the
           greatest
           excess
           
           being
           not
           above
           half
           a
           Minute
           ,
           yet
           if
           these
           ,
           seemingly
           but
           little
           Differences
           ,
           be
           added
           together
           for
           the
           space
           of
           a
           Month
           or
           Two
           together
           ,
           they
           will
           amount
           to
           a
           very
           considerable
           Sum
           of
           Time.
           
        
         
           Now
           ,
           to
           make
           the
           reason
           of
           this
           irregular
           Length
           of
           Days
           as
           plain
           as
           I
           can
           ,
           be
           pleased
           to
           take
           notice
           ,
           That
           as
           Natural
           Days
           are
           that
           space
           of
           Time
           in
           which
           the
           Sun
           (
           or
           ,
           as
           others
           think
           ,
           the
           Earth
           )
           by
           the
           Motion
           of
           those
           Orbs
           ,
           that
           divide
           Time
           into
           Days
           ,
           is
           moved
           round
           just
           one
           whole
           diurnal
           Revolution
           ,
           or
           passes
           from
           the
           Meridian
           ,
           or
           Twelve
           a
           Clock
           Point
           of
           one
           Day
           to
           that
           of
           the
           next
           ;
           so
           it
           must
           follow
           that
           all
           such
           natural
           Days
           cannot
           be
           of
           a
           true
           and
           equal
           Length
           ,
           unlese
           the
           Sun
           ,
           in
           that
           space
           of
           Time
           does
           also
           move
           in
           such
           a
           manner
           in
           his
           annual
           Orb
           ,
           as
           that
           the
           Equinoctial
           may
           be
           always
           divided
           into
           equal
           Parts
           by
           those
           Meridians
           ,
           on
           which
           the
           Sun
           is
           upon
           each
           particular
           Day
           :
           But
           that
           this
           is
           not
           done
           ,
           is
           plain
           to
           all
           that
           are
           verst
           in
           Astronomy
           ,
           and
           rightly
           understands
           the
           Use
           of
           the
           Globe
           .
        
         
         
           This
           ,
           an
           exact
           Table
           of
           the
           Sun
           's
           Right
           Ascensions
           does
           demonstrate
           ,
           for
           by
           that
           't
           will
           be
           found
           that
           the
           Meridian
           Sun
           of
           each
           Day
           doth
           not
           divide
           the
           Equinoctial
           into
           equal
           parts
           ,
           their
           Differences
           not
           being
           equal
           ,
           but
           more
           on
           some
           Days
           than
           they
           are
           on
           others
           ;
           and
           these
           their
           Differences
           will
           appear
           yet
           more
           plain
           and
           visible
           ,
           if
           you
           will
           be
           but
           at
           the
           Pains
           to
           compute
           what
           the
           Right
           Ascensions
           amount
           to
           in
           to
           or
           20
           Days
           Time
           ,
           in
           some
           parts
           of
           the
           Year
           ,
           and
           compare
           that
           with
           those
           of
           the
           like
           Number
           of
           Days
           in
           some
           other
           part
           .
        
         
           So
           also
           ,
           if
           on
           the
           Globe
           you
           mark
           out
           on
           the
           Ecliptick
           10
           or
           20
           Days
           Motion
           of
           the
           Sun
           ,
           as
           't
           is
           found
           set
           down
           in
           an
           exact
           Ephemeris
           or
           Almanack
           ,
           that
           shews
           the
           Sun
           's
           true
           Place
           ;
           and
           passing
           this
           under
           the
           brazen
           Meridian
           ,
           note
           what
           number
           of
           Degrees
           on
           the
           Equinoctial
           are
           included
           in
           that
           Space
           ,
           the
           which
           compare
           with
           those
           of
           the
           like
           number
           of
           Days
           Motion
           in
           some
           other
           part
           of
           the
           Ecliptick
           ,
           and
           the
           Degrees
           so
           compared
           will
           be
           found
           to
           differ
           ,
           or
           be
           more
           in
           Number
           in
           some
           
           Places
           than
           they
           are
           in
           others
           ;
           which
           plainly
           demonstrates
           the
           Thing
           asserted
           .
        
         
           Now
           the
           Reason
           of
           these
           Differences
           in
           the
           Right
           Ascensions
           ,
           and
           ,
           by
           consequence
           in
           the
           different
           Lengths
           of
           Days
           proceeds
           ,
           in
           the
           First
           Place
           ,
           from
           the
           cross
           Position
           of
           the
           Zodiack
           and
           the
           Equinoctial
           ,
           which
           on
           Globes
           do
           represent
           the
           Circles
           of
           the
           Sun
           's
           yearly
           and
           dayly
           Motion
           ;
           for
           the
           Course
           of
           the
           Sun
           's
           daily
           Motion
           being
           directly
           from
           East
           to
           West
           ,
           and
           the
           Circle
           of
           his
           yearly
           Motion
           being
           in
           position
           Cross-ways
           thereunto
           from
           the
           almost
           South
           West
           to
           the
           North
           East
           ,
           as
           by
           the
           Globe
           is
           apparent
           ,
           it
           follows
           that
           the
           Right
           Ascension
           will
           be
           still
           unequal
           ;
           for
           't
           is
           impossible
           that
           the
           Sun
           ,
           in
           his
           Motion
           ,
           near
           Aries
           and
           Libra
           ,
           where
           the
           Zodiack
           lyes
           cross
           the
           Equinoctial
           ,
           should
           in
           any
           certain
           number
           of
           Days
           make
           the
           same
           Number
           of
           Degrees
           in
           Right
           Ascension
           ,
           as
           he
           will
           do
           near
           the
           two
           Tropicks
           of
           Cancer
           and
           Capricorn
           ,
           where
           the
           Ecliptick
           runs
           in
           a
           manner
           parallel
           to
           the
           Equinoctial
           Circle
           .
        
         
         
           And
           accordingly
           't
           is
           sound
           by
           the
           best
           Tables
           of
           Right
           Ascension
           ,
           that
           the
           Right
           Ascensions
           belonging
           to
           10
           Days
           Motion
           of
           the
           Sun
           ,
           near
           the
           Tropick
           of
           Capricorn
           ,
           amounts
           to
           about
           11
           Degrees
           30
           Minutes
           ,
           whereas
           that
           of
           the
           same
           Number
           of
           Days
           ,
           near
           the
           Equinoctial
           Points
           of
           Aries
           or
           Libra
           will
           be
           found
           to
           be
           hardly
           9
           Degrees
           .
        
         
           And
           as
           the
           Right
           Ascensions
           of
           the
           Tropicks
           differ
           from
           those
           of
           the
           Equinoctial
           Parts
           of
           the
           Ecliptick
           ,
           so
           the
           Right
           Ascensions
           of
           one
           Tropick
           differs
           from
           that
           of
           the
           other
           :
           Now
           the
           Cause
           of
           this
           differs
           from
           the
           Cause
           of
           the
           former
           unequalities
           ,
           for
           this
           proceeds
           from
           the
           excentricity
           of
           the
           Centre
           of
           the
           Earth
           and
           the
           Centre
           of
           the
           Sun
           's
           yearly
           Orb
           ;
           for
           the
           Centre
           of
           the
           Earth
           ,
           on
           which
           we
           live
           ,
           not
           being
           the
           same
           with
           the
           Centre
           of
           the
           Ecliptick
           ,
           in
           which
           the
           Sun
           moves
           ,
           but
           distant
           from
           it
           ,
           as
           some
           Astronomers
           affirm
           ,
           about
           316000
           Miles
           ,
           it
           follows
           that
           there
           must
           be
           a
           greater
           part
           of
           the
           Sun's
           Orb
           on
           one
           Side
           of
           the
           Centre
           of
           the
           Earth
           than
           there
           is
           on
           the
           other
           ;
           for
           which
           Reason
           ,
           though
           the
           Sun
           moves
           
           equally
           each
           Day
           in
           the
           Circle
           of
           his
           yearly
           Course
           ,
           yet
           to
           us
           he
           seems
           to
           move
           faster
           in
           some
           Parts
           thereof
           than
           he
           does
           in
           others
           ,
           and
           that
           makes
           the
           Right
           Ascensions
           greater
           near
           one
           Tropick
           than
           they
           are
           near
           the
           other
           .
        
         
           And
           accordingly
           ,
           by
           the
           Tables
           of
           the
           Sun's
           Motion
           't
           is
           found
           that
           he
           takes
           up
           but
           about
           179
           Days
           in
           passing
           that
           part
           of
           the
           Ecliptick
           between
           Libra
           and
           Aries
           ,
           whereas
           between
           the
           Two
           Points
           of
           Aries
           and
           Libra
           he
           spends
           above
           186
           ,
           so
           that
           he
           is
           almost
           7
           Days
           more
           in
           passing
           the
           Summer
           half
           of
           the
           Ecliptick
           than
           he
           is
           in
           passing
           that
           of
           the
           Winter
           ,
           and
           this
           seemingly
           swift
           and
           slow
           Motion
           of
           the
           Sun
           is
           the
           Cause
           that
           the
           Right
           Ascensions
           of
           10
           Days
           Motion
           near
           the
           Winter
           Tropick
           are
           60
           Minutes
           ,
           or
           a
           whole
           Degree
           more
           than
           those
           of
           the
           same
           Number
           of
           Days
           near
           that
           of
           the
           Summer
           one
           .
        
         
           The
           Right
           Ascensions
           of
           10
           Days
           Time
           near
           the
           2
           Equinoctial
           Points
           do
           also
           differ
           somewhat
           ;
           for
           those
           of
           10
           Days
           Time
           ,
           near
           Aries
           ,
           are
           less
           by
           30
           Minutes
           than
           those
           near
           Libra
           ;
           the
           Reason
           of
           which
           is
           from
           hence
           ,
           in
           that
           
           the
           Suns
           greatest
           and
           nearest
           Distance
           to
           the
           Earth
           ,
           happens
           now
           in
           our
           Times
           to
           be
           about
           8
           Degrees
           and
           something
           more
           from
           the
           Tropick
           Points
           ,
           whereas
           had
           it
           fallen
           out
           exactly
           in
           the
           2
           Tropicks
           ,
           then
           the
           Right
           Ascensions
           near
           the
           Two
           Equinoctials
           would
           have
           been
           both
           alike
           .
        
         
           Now
           ,
           by
           what
           has
           been
           said
           ,
           I
           hope
           the
           true
           Reason
           of
           the
           unequal
           Lengths
           of
           Natural
           Days
           will
           plainly
           appear
           ,
           and
           by
           consequence
           Men
           will
           not
           hereafter
           be
           so
           unreasonably
           nice
           and
           curious
           ,
           as
           some
           have
           heretofore
           been
           to
           expect
           always
           an
           exact
           Agreement
           between
           their
           Clocks
           and
           the
           Sun
           ,
           for
           if
           there
           be
           from
           the
           Nature
           of
           the
           Fabrick
           of
           the
           World
           ,
           and
           the
           Celestial
           Orbs
           above
           us
           ,
           a
           necessity
           for
           those
           Differences
           ,
           as
           are
           found
           in
           the
           Sun
           's
           Right
           Ascensions
           ,
           and
           there
           being
           for
           that
           Reason
           a
           Necessity
           also
           that
           the
           Days
           bounded
           thereby
           should
           be
           unequal
           in
           proportion
           to
           those
           Differences
           .
           T
           is
           then
           plainly
           impossible
           that
           a
           Royal
           Pendulum
           (
           whose
           diurnal
           Revolutions
           are
           always
           equal
           ,
           and
           ,
           if
           well
           adjusted
           ,
           gives
           you
           the
           true
           Time
           of
           24
           Hours
           )
           should
           agree
           
           with
           the
           Sun
           ,
           which
           makes
           the
           length
           of
           Days
           almost
           continually
           to
           differ
           ,
           and
           to
           be
           sometimes
           more
           than
           24
           Hours
           ,
           and
           sometimes
           less
           .
        
         
           For
           ,
           in
           the
           first
           Place
           ,
           this
           makes
           it
           impossible
           to
           adjust
           a
           Clock
           well
           ,
           barely
           by
           the
           Sun
           :
           For
           suppose
           one
           should
           attempt
           to
           adjust
           a
           Clock
           when
           the
           Natural
           Days
           are
           not
           fully
           24
           Hours
           long
           ,
           as
           about
           the
           middle
           of
           March
           ,
           where
           ,
           as
           appears
           by
           the
           first
           annexed
           Table
           ,
           the
           Day
           wants
           20″
           of
           24
           Hours
           long
           ,
           this
           Clock
           brought
           to
           go
           correspondent
           to
           the
           Days
           in
           March
           ,
           shall
           in
           June
           finish
           his
           Pendulum
           Day
           or
           his
           two
           12
           Hours
           Revolutions
           before
           the
           Sun
           shall
           compleatly
           pass
           between
           one
           Meridian
           and
           another
           ,
           that
           is
           ,
           before
           the
           Sun
           shall
           pass
           from
           the
           Hour
           of
           12
           one
           Day
           ,
           to
           that
           of
           the
           Hour
           of
           12
           on
           the
           next
           ,
           because
           now
           the
           Natural
           Day
           is
           longer
           than
           24
           Hours
           by
           13″
           ,
           whereas
           the
           Day
           to
           which
           it
           was
           before
           adjusted
           was
           20″
           shorter
           than
           24
           Hours
           ,
           and
           by
           consequence
           the
           Pendulum
           Day
           of
           the
           Clock
           must
           be
           finished
           sooner
           in
           June
           by
           33″
           than
           the
           Natural
           Day
           ,
           and
           gain
           each
           Day
           33
           Seconds
           .
        
         
         
           On
           the
           contrary
           ,
           if
           a
           Clock
           could
           be
           adjusted
           to
           the
           Sun
           in
           the
           Month
           of
           December
           ,
           at
           which
           Time
           the
           Natural
           Day
           is
           longest
           ,
           being
           then
           31″
           ,
           or
           half
           a
           Minute
           above
           24
           Hours
           in
           length
           ,
           this
           Clock
           ,
           when
           Natural
           Days
           are
           shortest
           ,
           as
           in
           March
           ,
           where
           they
           want
           20″
           of
           24
           Hours
           ,
           this
           Clock
           ,
           I
           say
           ,
           shall
           not
           then
           finish
           his
           diurnal
           Revolutions
           in
           so
           little
           a
           Time
           as
           those
           Days
           shall
           be
           accomplished
           ,
           and
           by
           consequence
           shall
           go
           each
           Day
           50″
           too
           slow
           ,
           because
           those
           Days
           in
           March
           are
           shorter
           by
           50″
           than
           those
           in
           December
           ,
           to
           which
           your
           Clock
           is
           supposed
           to
           be
           adjusted
           .
        
         
           Supposed
           to
           be
           adjusted
           ,
           I
           say
           ,
           for
           to
           do
           it
           exactly
           by
           the
           Sun
           ,
           we
           affirm
           to
           be
           impossible
           ,
           for
           the
           Length
           of
           Days
           continually
           altering
           ,
           he
           that
           would
           adjust
           a
           Clock
           to
           the
           Sun
           must
           be
           always
           altering
           of
           it
           accordingly
           ;
           and
           if
           he
           should
           accidentally
           bring
           it
           to
           go
           slow
           enough
           ,
           as
           he
           thinks
           ,
           for
           some
           Days
           ,
           such
           as
           those
           long
           ones
           in
           December
           are
           ,
           the
           length
           of
           the
           Day
           soon
           altering
           ,
           and
           becoming
           shorter
           ,
           he
           must
           again
           alter
           the
           Length
           of
           his
           Pendulum
           ,
           to
           make
           it
           go
           equal
           to
           Days
           that
           are
           now
           shorter
           ,
           
           and
           so
           not
           understanding
           the
           Nature
           of
           Time
           truly
           ,
           nor
           of
           what
           Length
           a
           mean
           or
           middle
           Day
           is
           ,
           he
           will
           ,
           in
           Hopes
           of
           making
           it
           go
           always
           true
           ,
           be
           continually
           altering
           of
           it
           ,
           as
           he
           sees
           it
           vary
           ,
           and
           that
           without
           ever
           being
           so
           happy
           as
           to
           make
           it
           keep
           the
           Time
           desired
           ;
           for
           't
           is
           impossible
           a
           Motion
           that
           keeps
           always
           the
           same
           Time
           that
           its
           particular
           Length
           or
           pitch
           of
           Pendulum
           does
           admit
           of
           ,
           can
           be
           so
           adjusted
           by
           the
           bare
           Sun
           ,
           as
           to
           accord
           therewith
           in
           all
           those
           various
           lengths
           of
           Days
           ,
           which
           are
           made
           by
           its
           either
           slow
           or
           swift
           Motion
           .
        
         
           Since
           then
           things
           are
           thus
           ,
           it
           remains
           that
           we
           shew
           ,
           How
           by
           Art
           that
           may
           be
           done
           which
           by
           meer
           Natural
           Observation
           can
           never
           be
           effected
           ;
           that
           is
           ,
           by
           what
           means
           a
           Clock
           ,
           regulated
           by
           a
           Royal
           Pendulum
           ,
           may
           be
           adjusted
           to
           such
           a
           middle
           Pitch
           of
           Motion
           as
           to
           make
           in
           a
           compleat
           Year
           just
           365
           equal
           Revolutions
           ,
           or
           so
           that
           each
           of
           its
           24
           Hours
           may
           be
           the
           same
           for
           Length
           ,
           as
           the
           365th
           part
           of
           a
           Year
           is
           ,
           which
           is
           indeed
           the
           true
           Time
           of
           a
           24
           Hour
           Day
           ,
           and
           that
           's
           the
           nearest
           and
           the
           most
           exact
           pitch
           to
           which
           't
           is
           possible
           
           to
           adjust
           the
           best
           of
           Pendulums
           .
        
         
           Now
           this
           is
           only
           to
           be
           done
           by
           the
           help
           of
           an
           exact
           Table
           of
           Equations
           ,
           which
           shall
           as
           nearly
           as
           't
           is
           possible
           give
           you
           the
           true
           Length
           of
           every
           Day
           ,
           so
           that
           knowing
           by
           this
           means
           not
           only
           which
           Days
           are
           truly
           24
           Hours
           long
           ,
           but
           also
           which
           are
           shorter
           and
           which
           are
           longer
           ,
           't
           will
           be
           easy
           then
           to
           know
           what
           must
           be
           taken
           from
           some
           or
           added
           unto
           others
           ,
           to
           make
           them
           equal
           to
           them
           that
           are
           truly
           24
           Hours
           ,
           which
           in
           short
           is
           the
           true
           Business
           of
           the
           Equation
           of
           Time
           :
           And
           though
           this
           cannot
           be
           done
           in
           the
           Natural
           Day
           it self
           ,
           yet
           knowing
           how
           much
           all
           Days
           do
           differ
           from
           24
           Hours
           ,
           the
           Motion
           of
           a
           Clock
           may
           yet
           be
           adjusted
           thereby
           to
           a
           true
           Pendulum
           or
           24
           Hour
           Day
           ,
           by
           making
           it
           either
           lose
           or
           gain
           so
           much
           as
           the
           Days
           do
           exceed
           or
           fall
           short
           of
           24
           Hours
           .
        
         
           And
           this
           may
           well
           enough
           be
           performed
           by
           the
           Tables
           of
           Signs
           and
           Tangents
           ,
           for
           by
           these
           you
           may
           readily
           frame
           a
           Table
           of
           the
           Sun
           's
           natural
           right
           Ascensions
           ;
           and
           this
           shall
           shew
           you
           what
           Degrees
           of
           the
           Equinoctial
           are
           each
           Day
           
           upon
           the
           true
           Meridian
           ,
           when
           the
           Sun
           comes
           to
           it
           .
           Now
           these
           being
           in
           their
           measure
           of
           Degrees
           and
           Minutes
           sometimes
           more
           ,
           and
           sometimes
           less
           ,
           you
           must
           next
           find
           out
           what
           a
           mean
           or
           equal
           right
           Ascension
           will
           amount
           to
           by
           dividing
           the
           360
           Degrees
           of
           the
           Equinoctial
           into
           365
           Parts
           ,
           agreeable
           to
           the
           number
           of
           Days
           contained
           in
           a
           Year
           ;
           then
           compare
           each
           natural
           right
           Ascension
           with
           the
           mean
           ones
           ,
           and
           by
           substracting
           the
           lesser
           from
           the
           greater
           ,
           you
           will
           by
           turning
           the
           differences
           between
           them
           into
           Time
           ,
           come
           to
           know
           their
           true
           Equation
           ,
           that
           is
           ,
           how
           much
           each
           Day
           is
           longer
           or
           shorter
           than
           24
           Hours
           ;
           for
           so
           much
           as
           the
           natural
           right
           Ascension
           is
           more
           than
           the
           Mean
           in
           Time
           ,
           so
           much
           is
           that
           Day
           longer
           than
           24
           Hours
           ;
           and
           so
           much
           as
           the
           Natural
           is
           less
           than
           the
           Mean
           ,
           so
           much
           is
           that
           Day
           wanting
           of
           24
           Hours
           long
           .
        
         
           But
           Men
           may
           now
           well
           spare
           themselves
           the
           trouble
           of
           doing
           this
           ,
           in
           regard
           that
           Tables
           of
           this
           nature
           are
           already
           published
           by
           divers
           excellent
           and
           learned
           Men
           :
           As
           first
           ,
           by
           Mr.
           Hugens
           ,
           Printed
           Novem.
           29.
           
           Of
           the
           
             Philosophical
             Transactions
          
           :
           
           Secondly
           ,
           by
           Mr.
           Flamsteed
           ,
           commonly
           made
           use
           of
           by
           Mr.
           Tompion
           ,
           Printed
           also
           in
           
           Parker's
           Almanack
           .
           Thirdly
           ,
           by
           Mr.
           Molyneux
           in
           his
           
             Sciothericum
             Telescopicum
          
           ,
           or
           ingenious
           Tract
           of
           the
           
             Telescope
             Dial.
          
           Fourthly
           ,
           by
           the
           learned
           Dr.
           
             William
             Salmon
          
           ,
           in
           his
           Almanack
           for
           this
           Year
           1694.
           
           And
           fifthly
           ,
           by
           Mr.
           
             Samuel
             Watson
          
           ,
           the
           curious
           Contriver
           of
           that
           rare
           
             Celestial
             Orbitery
          
           ,
           now
           in
           the
           present
           Queen
           
           Mary's
           possession
           ;
           in
           each
           of
           which
           the
           Equations
           are
           nearly
           enough
           the
           same
           for
           substance
           ,
           as
           you
           will
           soon
           find
           by
           substracting
           any
           of
           their
           Numbers
           from
           the
           greater
           next
           it
           ;
           and
           't
           is
           not
           material
           which
           you
           choose
           ,
           provided
           you
           understand
           them
           rightly
           ;
           but
           for
           my
           part
           I
           believe
           ,
           from
           good
           Experience
           ,
           there
           are
           not
           many
           that
           truly
           do
           this
           ;
           and
           therefore
           having
           for
           some
           Reasons
           which
           I
           shall
           not
           now
           mention
           ,
           made
           choice
           of
           Mr.
           
           Hugens's
           Equations
           ,
           for
           the
           Uses
           intended
           in
           this
           Work
           ;
           I
           have
           thought
           fit
           to
           cast
           them
           into
           such
           peculiar
           Forms
           of
           my
           own
           ,
           as
           I
           judge
           more
           plain
           and
           natural
           than
           they
           are
           in
           the
           Form
           in
           which
           I
           find
           them
           published
           in
           the
           
             Philosophical
             Transactions
          
           ;
           and
           I
           
           believe
           will
           ,
           by
           the
           generality
           of
           them
           that
           are
           possest
           of
           
             Royal
             Pendulums
          
           ,
           be
           better
           understood
           too
           .
        
         
           Now
           in
           order
           to
           understand
           rightly
           the
           first
           Equation
           Table
           for
           length
           of
           Days
           ;
           take
           notice
           ,
           that
           the
           first
           Colume
           contains
           the
           Days
           common
           to
           every
           Month
           ,
           the
           other
           12
           Columes
           belong
           to
           the
           Months
           whose
           Names
           are
           set
           over
           them
           ;
           in
           the
           which
           ,
           D
           24.
           denotes
           which
           Days
           in
           the
           Year
           are
           just
           24
           Hours
           long
           ;
           and
           where
           you
           find
           
             red
             Figures
          
           ,
           there
           the
           Days
           are
           so
           many
           Seconds
           of
           Time
           above
           24
           Hours
           long
           ,
           as
           the
           Figures
           express
           ;
           and
           where-ever
           the
           Figures
           are
           black
           ,
           there
           the
           Days
           want
           so
           much
           of
           being
           24
           Hours
           ,
           as
           those
           Figures
           in
           Seconds
           of
           Time
           do
           amount
           to
           ;
           so
           that
           by
           the
           Colour
           of
           the
           Figures
           ,
           you
           may
           discern
           at
           what
           times
           the
           Clock
           will
           naturally
           gain
           or
           lose
           ,
           and
           by
           the
           sum
           thereof
           ,
           you
           will
           know
           the
           time
           so
           lost
           or
           got
           each
           Day
           .
        
         
           The
           Table
           being
           thus
           briefly
           explained
           ,
           I
           shall
           now
           shew
           ,
           how
           thereby
           to
           adjust
           a
           
             Royal
             Pendulum
          
           so
           exactly
           ,
           as
           that
           its
           Diurnal
           ,
           or
           Daily
           Revolutions
           ,
           which
           is
           that
           of
           its
           twice
           12
           Hours
           going
           ,
           
           may
           be
           equal
           to
           the
           true
           24
           Hour-Day
           :
           To
           do
           this
           ,
           let
           the
           Clock
           be
           set
           right
           to
           the
           Sun
           ,
           and
           note
           the
           Day
           on
           which
           't
           is
           so
           set
           ;
           then
           let
           it
           continue
           going
           till
           you
           find
           the
           Time
           given
           by
           the
           Sun
           ,
           and
           that
           which
           the
           Clock
           shews
           ,
           visibly
           to
           disagree
           ;
           observe
           then
           how
           much
           the
           difference
           is
           ;
           that
           is
           ,
           how
           much
           't
           is
           either
           too
           fast
           ,
           or
           too
           slow
           ;
           then
           count
           how
           much
           the
           whole
           number
           of
           Seconds
           amounts
           to
           ,
           included
           between
           the
           two
           Days
           of
           your
           first
           setting
           and
           last
           observing
           ,
           save
           one
           ,
           by
           allowing
           60
           Seconds
           to
           one
           Minute
           of
           Time
           ,
           and
           if
           the
           difference
           between
           the
           Clock
           and
           the
           Sun
           be
           equal
           to
           what
           the
           sum
           of
           Equations
           so
           cast
           up
           amounts
           to
           ,
           then
           is
           the
           Pendulum
           very
           well
           and
           truly
           ajusted
           .
        
         
           But
           in
           doing
           this
           ,
           that
           is
           ,
           in
           summing
           up
           the
           Equations
           contain'd
           in
           the
           Table
           ,
           you
           must
           be
           sure
           to
           observe
           ,
           as
           I
           said
           ,
           to
           take
           in
           the
           Equation
           of
           the
           Day
           on
           which
           you
           set
           it
           ,
           and
           leave
           out
           that
           which
           belongs
           to
           the
           Day
           of
           your
           last
           observing
           ;
           for
           should
           the
           last
           be
           taken
           in
           ,
           they
           would
           make
           the
           sum
           of
           Seconds
           lost
           or
           got
           to
           be
           so
           much
           more
           than
           the
           truth
           ,
           
           and
           if
           it
           hath
           both
           got
           or
           lost
           during
           the
           time
           it
           has
           gone
           ,
           as
           it
           sometimes
           may
           happen
           ,
           when
           the
           Sun
           appears
           not
           of
           a
           long
           time
           ,
           to
           make
           an
           Observation
           ,
           then
           you
           must
           substract
           the
           lesser
           sum
           of
           Equations
           from
           the
           greater
           ,
           and
           the
           Remainder
           shall
           shew
           the
           true
           time
           lost
           or
           got
           ;
           as
           if
           the
           gaining
           Numbers
           be
           20
           ,
           and
           the
           losing
           15
           ,
           then
           the
           true
           time
           it
           should
           have
           got
           ,
           is
           just
           5
           Minutes
           .
        
         
           But
           if
           the
           Clock
           have
           gone
           more
           too
           fast
           or
           too
           slow
           ,
           than
           the
           sum
           of
           the
           Equations
           in
           the
           Table
           amounts
           to
           ,
           then
           must
           the
           Motion
           of
           it
           be
           altered
           accordingly
           ,
           by
           screwing
           up
           the
           Bob
           ,
           or
           making
           the
           Pendulum
           shorter
           ,
           in
           case
           it
           has
           gone
           too
           slow
           ,
           or
           by
           letting
           the
           Bob
           down
           longer
           ,
           in
           case
           it
           has
           gone
           100
           fast
           ;
           and
           then
           having
           set
           it
           true
           to
           the
           Sun
           a
           second
           time
           ,
           try
           it
           again
           ,
           as
           you
           were
           before
           directed
           ,
           and
           if
           its
           disagreement
           with
           the
           Sun
           be
           not
           yet
           answerable
           to
           the
           sum
           of
           the
           Equations
           belonging
           to
           the
           time
           it
           has
           gone
           in
           ,
           let
           the
           Bob
           be
           rectified
           a
           second
           time
           ,
           and
           let
           the
           Clock
           be
           set
           a
           new
           ;
           and
           thus
           continue
           to
           do
           ,
           till
           you
           find
           its
           difference
           with
           the
           Sun
           to
           be
           nearly
           equal
           to
           the
           
           sum
           of
           Equations
           contain'd
           in
           the
           Table
           .
        
         
           Now
           when
           the
           Clock
           is
           by
           this
           means
           adjusted
           right
           ,
           its
           Daily
           Revolutions
           ,
           or
           each
           24
           Hours
           time
           of
           its
           going
           will
           be
           equal
           to
           the
           true
           24
           Hour-day
           ,
           or
           the
           just
           365th
           part
           of
           a
           Year
           ;
           for
           if
           a
           Year
           be
           exactly
           divided
           into
           365
           parts
           ,
           each
           of
           these
           parts
           will
           be
           equal
           in
           length
           to
           the
           24
           Hours
           motion
           of
           a
           welladjusted
           Pendulum
           ,
           and
           the
           Motion
           of
           a
           Pendulum
           so
           exactly
           regulated
           ,
           will
           be
           such
           ,
           that
           if
           it
           be
           at
           any
           time
           set
           right
           ,
           and
           so
           let
           go
           the
           whole
           Year
           about
           ,
           it
           will
           the
           same
           Day
           Twelve-month
           agree
           nearly
           with
           the
           Dial
           to
           which
           it
           was
           set
           a
           Year
           before
           .
        
         
           But
           yet
           in
           its
           Course
           of
           thus
           going
           a
           whole
           Year
           round
           ,
           't
           will
           sometimes
           be
           found
           to
           differ
           very
           much
           from
           the
           same
           Dial
           't
           was
           at
           first
           set
           to
           ;
           and
           these
           various
           Differences
           which
           its
           Motion
           will
           be
           subject
           to
           ,
           will
           still
           be
           agreeable
           to
           what
           the
           nature
           of
           the
           time
           was
           't
           was
           set
           in
           :
           For
           set
           at
           one
           time
           of
           the
           Year
           ,
           t'
           will
           be
           always
           more
           or
           less
           too
           slow
           ,
           till
           the
           time
           of
           its
           coming
           right
           the
           same
           Day
           Twelve
           month
           :
           Set
           at
           another
           
           time
           't
           will
           go
           always
           too
           fast
           till
           just
           the
           same
           Day
           Twelve
           month
           :
           Set
           at
           some
           other
           time
           ,
           't
           will
           go
           sometimes
           too
           fast
           ,
           and
           sometimes
           too
           slow
           ;
           the
           Reason
           of
           which
           is
           plain
           and
           evident
           by
           the
           Table
           of
           Equations
           that
           gives
           the
           length
           of
           natural
           Days
           .
        
         
           For
           it
           appears
           by
           that
           ,
           that
           in
           all
           that
           Space
           where
           
             black
             Figures
          
           are
           found
           ,
           there
           the
           Clock
           will
           still
           go
           too
           slow
           ,
           because
           the
           
             Pendulum
             Day
          
           is
           longer
           than
           the
           
             Natural
             Day
          
           :
           On
           the
           contrary
           ,
           where
           the
           
             red
             Figures
          
           are
           found
           ,
           there
           a
           well
           adjusted
           Clock
           will
           go
           always
           too
           fast
           ,
           because
           there
           the
           
             Pendulum
             Day
          
           is
           shorter
           than
           the
           
             Natural
             Day
          
           ,
           and
           by
           consequence
           is
           finish'd
           before
           it
           .
        
         
           Now
           't
           is
           plain
           ,
           that
           if
           a
           Clock
           be
           set
           right
           to
           the
           Sun
           the
           First
           of
           February
           ,
           it
           must
           go
           all
           the
           Year
           after
           too
           slow
           ,
           because
           the
           losing
           between
           that
           and
           the
           Fourth
           of
           May
           ,
           is
           so
           much
           ,
           that
           it
           never
           gains
           it
           up
           till
           the
           very
           last
           part
           of
           its
           Years
           going
           :
           On
           the
           contrary
           ,
           if
           it
           be
           set
           right
           the
           Twenty
           third
           of
           October
           ,
           it
           will
           gain
           so
           much
           by
           the
           last
           of
           January
           ,
           as
           no
           Loss
           shall
           afterwards
           countervail
           ;
           but
           that
           in
           the
           very
           last
           part
           of
           its
           Years
           
           going
           between
           the
           Sixteenth
           of
           July
           ,
           and
           the
           Twenty
           first
           of
           October
           .
           'T
           is
           likewise
           as
           plain
           ,
           that
           if
           a
           Clock
           be
           set
           right
           the
           Fourth
           of
           May
           ,
           't
           will
           then
           in
           the
           time
           of
           a
           Years
           going
           ,
           be
           both
           too
           fast
           ,
           and
           too
           slow
           ;
           for
           the
           gaining
           at
           first
           being
           less
           than
           the
           next
           losing
           ,
           it
           will
           be
           too
           slow
           by
           the
           Twenty
           first
           of
           October
           ,
           though
           't
           was
           too
           fast
           the
           Fifteenth
           of
           July
           ;
           and
           the
           like
           will
           happen
           if
           it
           be
           set
           right
           the
           Seventeenth
           of
           July
           ;
           for
           the
           losing
           that
           follows
           being
           less
           than
           the
           next
           gaining
           between
           October
           24
           ,
           and
           January
           31.
           it
           must
           by
           consequence
           be
           sometimes
           too
           fast
           ,
           and
           sometimes
           too
           slow
           .
        
         
           So
           that
           as
           a
           Clock
           may
           happen
           to
           be
           set
           ,
           it
           may
           in
           some
           considerable
           time
           of
           going
           ,
           be
           almost
           half
           an
           Hour
           too
           fast
           ,
           or
           half
           an
           Hour
           too
           slow
           ,
           though
           as
           to
           its
           own
           Motion
           it
           go
           exact
           and
           true
           ,
           as
           it
           should
           do
           ;
           and
           for
           this
           there
           is
           no
           help
           ,
           unless
           you
           understand
           well
           the
           nature
           of
           Time
           ,
           and
           know
           when
           and
           in
           what
           manner
           to
           set
           the
           Clock
           ,
           so
           as
           that
           for
           some
           good
           length
           of
           time
           after
           ,
           he
           may
           so
           humour
           the
           Sun's
           motion
           ,
           as
           never
           to
           be
           very
           far
           distant
           from
           
           it
           ;
           but
           sometimes
           too
           fast
           a
           little
           ,
           and
           in
           a
           little
           time
           fall
           back
           again
           as
           it
           were
           ,
           and
           so
           come
           to
           be
           right
           therewith
           ,
           and
           then
           in
           a
           little
           time
           after
           be
           a
           little
           too
           slow
           .
        
         
           Now
           therefore
           in
           order
           to
           the
           reducing
           of
           the
           Motion
           of
           a
           well
           adjusted
           Clock
           much
           nearer
           the
           time
           given
           by
           the
           Sun
           ,
           than
           as
           yet
           any
           known
           Rule
           will
           direct
           us
           ;
           I
           have
           with
           great
           Care
           and
           Pains
           ,
           Composed
           a
           Second
           Table
           of
           Equations
           ,
           that
           shews
           how
           a
           good
           and
           well
           adjusted
           Pendulum
           may
           be
           kept
           all
           the
           Year
           round
           within
           a
           great
           deal
           less
           for
           the
           most
           part
           than
           3′
           45″
           of
           the
           time
           given
           by
           the
           Sun
           ,
           or
           the
           4th
           part
           of
           a
           quarter
           of
           an
           Hour
           ,
           which
           is
           so
           small
           a
           matter
           as
           not
           to
           be
           perceived
           in
           common
           business
           :
           Now
           in
           the
           explanation
           of
           the
           
             Second
             Table
          
           ,
           note
           ;
        
         
           That
           the
           
             First
             Colume
          
           contains
           the
           Days
           of
           every
           Month
           ,
           the
           other
           
             Twelve
             Columes
          
           belong
           to
           the
           
             Twelve
             Months
          
           of
           the
           Year
           ,
           whose
           Names
           are
           plac'd
           over
           them
           ;
           the
           
             Black
             Figures
          
           in
           any
           part
           of
           the
           Columes
           ,
           shew
           where
           and
           how
           much
           a
           Clock
           in
           the
           
             Natural
             Course
          
           of
           its
           Motion
           ,
           according
           to
           the
           design
           of
           the
           Table
           ,
           
           will
           lose
           or
           go
           too
           slow
           ;
           the
           
             Red
             Figures
          
           shew
           in
           what
           parts
           of
           the
           Year
           ,
           and
           how
           much
           in
           Minutes
           and
           Seconds
           of
           Time
           ,
           the
           Clock
           will
           go
           too
           fast
           :
           As
           for
           the
           Days
           on
           which
           you
           find
           this
           Character
           ☉
           ,
           those
           Days
           I
           call
           
             Rectifying
             Days
          
           ,
           because
           on
           them
           the
           Clock
           is
           still
           to
           be
           new
           set
           ,
           in
           order
           to
           keep
           it
           the
           better
           within
           the
           Limits
           design'd
           by
           the
           Table
           :
           The
           Table
           thus
           explain'd
           ,
           I
           shall
           come
           now
           to
           shew
           you
           the
           Uses
           that
           may
           be
           made
           thereof
           .
        
         
           And
           first
           ,
           I
           will
           shew
           you
           how
           by
           the
           Table
           also
           ,
           as
           well
           as
           by
           the
           first
           ,
           a
           Clock
           maybe
           adjusted
           now
           to
           do
           this
           .
           Let
           this
           Clock
           be
           set
           to
           the
           Sun
           on
           any
           Day
           ,
           that
           is
           not
           a
           
             Rectifying
             Day
          
           ;
           observing
           this
           always
           ,
           to
           set
           it
           so
           much
           too
           fast
           ,
           as
           the
           Red
           ,
           or
           too
           slow
           ,
           as
           the
           
             Black
             Figures
          
           do
           express
           ,
           and
           then
           let
           it
           go
           for
           any
           considerable
           time
           ,
           provided
           it
           be
           not
           beyond
           a
           
             Rectifying
             Day
          
           ;
           and
           note
           whether
           its
           gain
           or
           loss
           be
           at
           any
           time
           equal
           to
           what
           the
           Table
           allows
           ;
           if
           it
           is
           ,
           then
           the
           Clock
           is
           truly
           adjusted
           ;
           but
           if
           it
           have
           lost
           ,
           or
           got
           more
           or
           less
           than
           it
           should
           do
           ,
           then
           rectifie
           the
           Bob
           ,
           by
           making
           it
           shorter
           ,
           if
           it
           have
           gone
           too
           
           slow
           ,
           or
           screwing
           it
           down
           longer
           ,
           in
           case
           it
           has
           gone
           too
           fast
           ;
           then
           set
           it
           anew
           ,
           and
           observe
           it
           a
           
             second
             time
          
           ,
           continuing
           your
           altering
           of
           the
           Bob
           ,
           and
           new
           setting
           ,
           till
           you
           have
           brought
           it
           to
           rights
           .
        
         
           For
           example
           ,
           Suppose
           you
           set
           it
           the
           Sixth
           of
           January
           ,
           you
           must
           upon
           this
           Day
           set
           it
           too
           slow
           by
           one
           Minute
           fifty
           two
           Seconds
           ,
           because
           the
           time
           is
           there
           set
           down
           in
           
             black
             Figures
          
           ;
           let
           it
           go
           till
           the
           11th
           of
           February
           ,
           on
           which
           Day
           if
           it
           be
           well
           adjusted
           ,
           it
           must
           be
           2′
           9″
           too
           fast
           ,
           because
           that
           sum
           of
           time
           is
           there
           set
           down
           in
           
             red
             Figures
          
           ;
           but
           if
           it
           should
           happen
           to
           be
           too
           slow
           ,
           or
           too
           fast
           for
           that
           time
           ,
           as
           suppose
           10
           Minutes
           too
           fast
           ,
           instead
           of
           2′
           9″
           ,
           you
           must
           then
           adjust
           it
           nearer
           by
           screwing
           the
           Nut
           of
           the
           Bob
           down
           lower
           ,
           or
           making
           it
           longer
           ,
           by
           what
           means
           soever
           the
           same
           is
           to
           be
           effected
           ;
           then
           set
           it
           anew
           just
           so
           much
           too
           fast
           as
           the
           Table
           for
           that
           Day
           does
           allow
           ,
           and
           so
           let
           it
           go
           till
           the
           4th
           or
           5th
           of
           March
           ,
           on
           which
           Day
           observe
           it
           again
           ,
           and
           correct
           what
           you
           find
           to
           be
           amiss
           in
           the
           Motion
           :
           Note
           hear
           ,
           that
           in
           adjusting
           by
           this
           Table
           ,
           you
           save
           your self
           the
           labour
           
           of
           casting
           up
           the
           sum
           of
           those
           Equations
           that
           belong
           to
           the
           time
           the
           Clock
           has
           gone
           in
           ,
           and
           by
           consequence
           the
           work
           of
           adjusting
           will
           be
           easier
           done
           by
           this
           ,
           than
           by
           the
           former
           Table
           .
        
         
           When
           the
           Clock
           is
           well
           adjusted
           ,
           it
           may
           then
           be
           kept
           the
           whole
           Year
           about
           as
           near
           the
           true
           time
           ,
           as
           the
           design
           of
           the
           Table
           allows
           of
           ,
           by
           the
           following
           method
           ;
           about
           12
           a
           Clock
           on
           any
           Day
           ,
           which
           is
           not
           a
           
             Rectifying
             Day
          
           ,
           set
           it
           so
           much
           too
           fast
           or
           too
           slow
           for
           the
           Sun
           ,
           as
           the
           Equation
           in
           the
           Table
           for
           that
           Day
           comes
           to
           ,
           that
           is
           ,
           too
           slow
           if
           the
           Figures
           are
           black
           ,
           or
           too
           fast
           if
           the
           Figures
           are
           red
           ;
           then
           let
           it
           go
           on
           till
           a
           
             Rectifying
             Day
          
           comes
           ,
           which
           is
           known
           in
           the
           Table
           by
           this
           mark
           ☉
           ,
           upon
           which
           Day
           about
           Noon
           ,
           set
           it
           backward
           from
           the
           place
           where
           the
           Hand
           then
           stood
           ,
           if
           the
           Figures
           on
           that
           Day
           are
           black
           ,
           or
           forward
           if
           they
           be
           red
           ,
           so
           much
           in
           time
           as
           the
           Figures
           express
           ,
           and
           observe
           to
           do
           the
           same
           upon
           every
           other
           
             Rectifying
             Day
          
           ,
           and
           then
           if
           the
           Clock
           be
           well
           adjusted
           ,
           it
           will
           go
           in
           all
           the
           
             intermediate
             parts
          
           ,
           according
           to
           the
           time
           given
           by
           the
           Table
           .
        
         
         
           Take
           one
           Example
           to
           make
           this
           plain
           ,
           Suppose
           you
           have
           not
           an
           Opportunity
           to
           set
           it
           till
           the
           18th
           of
           January
           ,
           the
           Equation
           for
           that
           Day
           is
           one
           Minute
           24
           Seconds
           too
           fast
           ;
           because
           the
           Figures
           are
           Red
           let
           it
           therefore
           be
           set
           so
           much
           too
           fast
           for
           the
           Sun
           ,
           and
           let
           it
           go
           till
           the
           8th
           of
           March
           ,
           on
           which
           Day
           ,
           about
           12
           a
           Clock
           ,
           set
           it
           forward
           from
           the
           Place
           the
           Hand
           is
           at
           7′
           29″
           ,
           because
           the
           Figures
           are
           red
           ,
           and
           then
           instead
           of
           being
           too
           slow
           ,
           as
           it
           before
           was
           ,
           it
           will
           be
           made
           to
           be
           3′
           45″
           too
           fast
           ;
           let
           it
           go
           till
           the
           31st
           of
           that
           Month
           ,
           and
           then
           set
           it
           again
           forward
           7′
           16″
           ;
           after
           which
           ,
           on
           the
           4th
           of
           June
           ,
           set
           it
           back
           5′
           8″
           ,
           because
           there
           you
           find
           Black
           Figures
           :
           On
           the
           22d
           of
           August
           set
           it
           also
           forward
           7′
           23″
           ,
           and
           on
           the
           12th
           of
           September
           7′
           17″
           ;
           set
           it
           forward
           likewise
           on
           the
           8th
           of
           October
           5′
           20″
           ,
           and
           also
           on
           the
           15th
           of
           November
           7′
           20″
           ;
           likewise
           on
           the
           3d
           of
           December
           let
           it
           be
           set
           back
           7′
           28″
           ,
           and
           on
           the
           18th
           7′
           3″
           .
           and
           on
           the
           first
           Day
           of
           the
           next
           Year
           7′
           8″
           :
           And
           thus
           ,
           with
           a
           very
           little
           Pains
           and
           Trouble
           you
           may
           keep
           a
           Clock
           near
           the
           true
           Time
           of
           the
           Day
           by
           a
           more
           easy
           Way
           and
           
           Method
           than
           has
           at
           any
           Time
           been
           practised
           heretofore
           .
        
         
           But
           in
           case
           you
           should
           miss
           rectifying
           your
           Clock
           on
           a
           rectifying
           Day
           ,
           then
           you
           must
           the
           next
           ,
           or
           any
           other
           Day
           following
           set
           him
           by
           the
           Sun
           so
           much
           too
           fast
           or
           too
           slow
           ,
           as
           the
           Nature
           of
           the
           Table
           requires
           ;
           and
           then
           he
           will
           again
           go
           on
           in
           that
           Order
           which
           the
           Design
           of
           the
           Table
           makes
           necessary
           ;
           that
           is
           ,
           he
           will
           then
           be
           capable
           of
           humoring
           the
           Suns
           Motion
           so
           far
           as
           that
           (
           between
           being
           sometimes
           a
           little
           too
           slow
           and
           othertimes
           a
           little
           too
           fast
           )
           't
           will
           ,
           with
           a
           little
           Rectification
           be
           always
           within
           less
           than
           a
           fourth
           Part
           of
           a
           quarter
           of
           an
           Hour
           of
           the
           true
           Time.
           In
           such
           Clocks
           as
           shew
           not
           Minutes
           the
           Time
           of
           setting
           must
           be
           guest
           at
           as
           well
           as
           you
           can
           .
        
         
           Now
           the
           Reason
           of
           thus
           setting
           a
           Clock
           sometimes
           backward
           and
           sometimes
           forwards
           ,
           upon
           the
           rectifying
           Days
           ,
           is
           this
           ,
           If
           a
           Clock
           ,
           at
           the
           beginning
           of
           the
           Year
           ,
           be
           set
           to
           the
           Sun
           ,
           according
           to
           the
           former
           Directions
           ,
           it
           will
           be
           too
           slow
           by
           the
           8th
           of
           March
           at
           Noon
           ,
           3′
           44″
           :
           Now
           the
           Design
           of
           the
           Table
           
           being
           to
           keep
           the
           Clock
           so
           as
           that
           it
           shall
           at
           no
           Time
           disagree
           with
           the
           Sun
           above
           3′
           45′
           ,
           or
           the
           fourth
           part
           of
           a
           quarter
           of
           an
           Hour
           :
           I
           then
           (
           to
           prevent
           its
           being
           more
           too
           slow
           ,
           as
           it
           will
           ,
           if
           let
           go
           longer
           )
           am
           necessitated
           to
           set
           it
           forward
           7′
           24″
           ,
           and
           then
           't
           will
           be
           too
           fast
           for
           the
           Sun
           3′
           45″
           .
           Now
           the
           Clock
           naturally
           losing
           ,
           at
           this
           Time
           of
           the
           Year
           ,
           it
           will
           again
           ,
           by
           the
           31st
           Day
           be
           too
           slow
           3′
           31″
           :
           Now
           the
           Clock
           being
           still
           naturally
           inclined
           to
           lose
           ,
           I
           therefore
           ,
           to
           prevent
           his
           being
           above
           3′
           45″
           too
           slow
           ,
           set
           him
           again
           7′
           16″
           forward
           from
           the
           Place
           where
           the
           Hand
           then
           stands
           ,
           and
           so
           he
           is
           again
           too
           fast
           for
           the
           Sun
           3′
           45′
           (
           which
           is
           the
           most
           that
           I
           suffer
           him
           to
           differ
           from
           the
           apparent
           Time
           )
           Now
           ,
           after
           this
           ,
           he
           going
           on
           ,
           for
           about
           9
           Weeks
           ,
           will
           the
           4th
           of
           June
           be
           too
           fast
           1′
           23″
           ,
           at
           which
           Time
           I
           set
           him
           back
           5′
           8″
           ,
           that
           so
           he
           may
           be
           now
           3′
           45″
           too
           slow
           ,
           for
           by
           thus
           doing
           he
           will
           continue
           going
           the
           longer
           ,
           before
           he
           will
           require
           to
           be
           again
           new
           set
           ;
           which
           next
           happens
           to
           be
           August
           22d
           ,
           which
           is
           above
           11
           Weeks
           Time
           :
           Now
           the
           like
           Reason
           is
           the
           Cause
           of
           his
           requiring
           to
           
           be
           set
           anew
           in
           any
           other
           Place
           or
           Part
           of
           the
           Year
           .
        
         
           And
           here
           I
           think
           fit
           to
           add
           one
           Caution
           to
           those
           that
           desire
           to
           adjust
           their
           Clocks
           very
           nicely
           ;
           and
           that
           is
           ,
           that
           among
           Dials
           ,
           they
           make
           use
           only
           of
           the
           horizontal
           or
           brass
           Dials
           ,
           which
           are
           fixt
           on
           Posts
           ,
           for
           no
           other
           can
           possibly
           give
           the
           Time
           so
           near
           the
           Truth
           ;
           neither
           on
           that
           should
           they
           make
           use
           of
           above
           one
           certain
           Hour
           ;
           and
           the
           nearer
           Noon
           that
           is
           the
           better
           ,
           for
           't
           is
           a
           difficult
           thing
           ,
           even
           for
           the
           best
           Masters
           in
           this
           Art
           ,
           to
           draw
           a
           Dial
           so
           true
           as
           to
           contain
           an
           equal
           Time
           between
           all
           its
           Hours
           ;
           which
           though
           in
           other
           Cases
           it
           be
           not
           very
           material
           ,
           yet
           in
           this
           of
           adjusting
           a
           Clock
           it
           may
           cause
           a
           considerable
           Error
           :
           Besides
           ,
           few
           Dials
           are
           fitted
           truly
           to
           the
           Latitudes
           in
           which
           they
           stand
           ;
           and
           if
           we
           could
           be
           certain
           that
           all
           were
           right
           ,
           as
           to
           these
           Particulars
           ,
           yet
           no
           Human
           Art
           can
           prevent
           the
           Sun's
           Refractions
           ,
           which
           as
           they
           make
           his
           Body
           appear
           much
           bigger
           when
           near
           the
           Horizon
           ,
           so
           they
           make
           him
           for
           a
           good
           part
           of
           the
           Day
           to
           shew
           to
           us
           higher
           than
           really
           he
           is
           ,
           and
           that
           must
           cause
           him
           to
           give
           a
           
           false
           Shadow
           on
           the
           truest
           Dial
           ;
           so
           that
           these
           particulars
           considered
           together
           ,
           't
           is
           plain
           that
           there
           can
           be
           no
           true
           account
           taken
           of
           the
           Time
           till
           near
           Noon
           ,
           or
           12
           a
           Clock
           ;
           and
           he
           that
           watches
           for
           that
           Moment
           need
           not
           matter
           the
           falsness
           of
           the
           Dial
           ,
           wrong
           Latitudes
           ,
           nor
           Refractions
           neither
           ,
           because
           upon
           the
           Meridian
           let
           the
           Sun
           be
           higher
           or
           lower
           ,
           yet
           it
           still
           gives
           you
           the
           true
           12
           a
           Clock
           .
        
         
           But
           in
           regard
           't
           is
           so
           very
           hard
           to
           distinguish
           to
           a
           Minute
           by
           the
           Shadow
           of
           the
           best
           Dial
           ,
           small
           ones
           not
           admitting
           of
           minute
           Divisions
           ,
           and
           in
           large
           ones
           the
           Haziness
           or
           Faintness
           of
           the
           Shadow
           renders
           a
           minute
           difficult
           to
           be
           discerned
           exactly
           ;
           't
           will
           therefore
           be
           better
           if
           instead
           of
           a
           Dial
           you
           make
           use
           of
           the
           following
           Device
           ,
           which
           I
           call
           a
           Meridian
           Cranny
           ;
           Take
           then
           Two
           plain
           and
           flat
           Plates
           or
           Boards
           ,
           about
           six
           or
           eight
           Inches
           square
           ,
           joyn
           them
           so
           close
           as
           that
           an
           old
           Groat
           or
           a
           Six
           Pence
           at
           the
           most
           may
           but
           pass
           between
           them
           ,
           let
           them
           be
           then
           fixed
           so
           as
           that
           the
           Chink
           or
           Cranny
           between
           them
           may
           respect
           ,
           as
           near
           as
           may
           be
           ,
           the
           Meridian
           or
           true
           South
           Point
           ,
           this
           will
           plainly
           give
           you
           the
           
           Time
           to
           half
           a
           Minute
           and
           less
           ,
           if
           you
           are
           careful
           to
           watch
           ,
           for
           the
           very
           first
           Beam
           ,
           that
           by
           the
           Sun
           's
           coming
           to
           the
           South
           shall
           be
           darted
           through
           it
           ,
           which
           may
           be
           perceived
           in
           a
           Moment
           by
           the
           help
           of
           a
           smooth
           Board
           or
           Plate
           of
           Brass
           ,
           made
           black
           ,
           and
           placed
           near
           it
           ,
           on
           the
           North
           Side
           ,
           to
           receive
           the
           Light
           ;
           by
           this
           means
           the
           true
           Time
           of
           the
           Sun
           's
           coming
           to
           the
           very
           same
           Point
           on
           the
           Meridian
           may
           be
           more
           exactly
           obtained
           than
           it
           can
           be
           by
           the
           best
           and
           truest
           Dial
           ,
           except
           such
           a
           one
           as
           is
           described
           by
           Mr.
           Molyneux
           in
           his
           
             Sciothericum
             Telescopicum
          
           .
        
         
           But
           now
           ,
           although
           the
           true
           Time
           of
           the
           Sun
           's
           coming
           to
           the
           South
           may
           ,
           by
           this
           means
           be
           more
           nearly
           obtained
           ,
           yet
           you
           will
           ,
           for
           all
           that
           ,
           find
           the
           Work
           of
           truly
           adjusting
           a
           Clock
           to
           be
           exceeding
           difficult
           ,
           especially
           to
           do
           it
           precisely
           ,
           when
           you
           have
           already
           brought
           to
           go
           prety
           nearly
           tru
           ,
           and
           this
           has
           made
           some
           to
           censure
           the
           Equation
           Tables
           ,
           as
           false
           ,
           because
           they
           could
           never
           adjust
           a
           Clock
           so
           as
           to
           acord
           therewith
           exactly
           ,
           or
           come
           Right
           the
           same
           Day
           twelve
           Month
           with
           
           that
           Dial
           ,
           to
           which
           it
           was
           set
           a
           Year
           before
           .
        
         
           Now
           ,
           that
           I
           may
           do
           right
           to
           Truth
           ,
           I
           affirm
           that
           this
           proceeds
           not
           from
           any
           material
           Defect
           in
           the
           Tables
           ,
           but
           either
           from
           their
           not
           rightly
           understanding
           which
           way
           to
           perform
           the
           Work
           they
           took
           in
           hand
           ,
           or
           from
           some
           other
           unavoidable
           Accidents
           ,
           with
           which
           Nature
           too
           often
           sportsher
           self
           in
           the
           Disappointment
           of
           Men's
           Designs
           :
           'T
           is
           probable
           indeed
           that
           there
           may
           be
           some
           Error
           in
           the
           Tables
           ,
           as
           suppose
           a
           Minute
           at
           the
           most
           ,
           this
           signifies
           little
           as
           to
           the
           Business
           in
           hand
           ,
           and
           if
           it
           did
           ,
           yet
           we
           ought
           to
           value
           a
           Guide
           that
           will
           bring
           us
           in
           sight
           of
           the
           thing
           we
           aim
           at
           ,
           rather
           than
           follow
           an
           apparent
           Uncertainty
           ,
           as
           I
           have
           proved
           those
           do
           that
           would
           attempt
           to
           adjust
           a
           Clock
           by
           barely
           setting
           of
           it
           true
           to
           the
           Sun
           ;
           there
           must
           be
           grains
           of
           Allowance
           given
           for
           Human
           Infirmity
           ,
           for
           no
           Man
           ,
           that
           understands
           himself
           ,
           dares
           pretend
           to
           an
           infallible
           certainty
           in
           things
           so
           much
           above
           him
           as
           those
           are
           about
           which
           Astronomy
           is
           conversant
           ,
           there
           's
           no
           measuring
           the
           divisions
           of
           the
           Celestial
           Spheres
           with
           Scale
           and
           
           Compasses
           ,
           all
           our
           Knowledge
           in
           things
           of
           this
           nature
           is
           derived
           from
           Observations
           made
           by
           Instruments
           ,
           which
           we
           know
           is
           so
           difficult
           to
           be
           done
           exactly
           ,
           that
           if
           ten
           Men
           should
           attempt
           at
           the
           same
           Time
           to
           find
           out
           the
           Sun's
           Declination
           (
           the
           Ground
           -
           work
           on
           which
           Equations
           are
           built
           )
           perhaps
           they
           would
           all
           differ
           ,
           as
           to
           their
           Accounts
           thereof
           :
           Now
           ,
           we
           know
           ,
           if
           the
           Premises
           are
           never
           so
           little
           out
           ,
           the
           Conclusions
           drawn
           therefrom
           can
           never
           be
           exactly
           and
           critically
           true
           .
        
         
           Therefore
           ,
           granting
           the
           Possibility
           of
           some
           inconsiderable
           Error
           in
           the
           Tables
           of
           Equation
           ,
           yet
           still
           we
           are
           sure
           of
           this
           ,
           That
           they
           come
           so
           near
           the
           Truth
           ,
           that
           perhaps
           no
           Man
           can
           here
           after
           Mend
           'em
           ;
           and
           the
           Work
           of
           adjusting
           a
           Clock
           is
           thereby
           made
           a
           hundred
           Times
           more
           easy
           than
           it
           would
           be
           to
           do
           it
           with
           out
           them
           :
           Besides
           ,
           we
           see
           that
           the
           most
           learned
           in
           Astronomy
           agree
           all
           of
           them
           as
           to
           the
           mean
           thing
           ,
           namely
           ,
           That
           there
           is
           such
           a
           thing
           as
           Difference
           in
           the
           length
           of
           Natural
           Days
           ,
           and
           their
           Tables
           all
           agree
           as
           to
           the
           Parts
           of
           the
           Year
           in
           which
           these
           Differences
           happen
           ;
           
           they
           also
           accord
           very
           nearly
           so
           as
           to
           the
           Quantity
           of
           Time
           that
           any
           natural
           Day
           is
           longer
           or
           shorter
           than
           24
           Hours
           ,
           and
           therefore
           we
           may
           very
           well
           rest
           satisfied
           that
           there
           are
           no
           material
           Errors
           committed
           therein
           ;
           and
           perhaps
           could
           we
           demonstrate
           any
           Table
           of
           Equations
           to
           be
           really
           exact
           to
           a
           tittle
           ,
           yet
           this
           Work
           of
           adjusting
           a
           Clock
           truly
           would
           not
           be
           found
           more
           easy
           to
           do
           then
           than
           now
           it
           is
           ,
           for
           much
           of
           this
           depends
           not
           only
           upon
           the
           right
           understanding
           which
           way
           to
           perform
           best
           the
           Work
           we
           are
           about
           ,
           but
           on
           the
           Constant
           Temper
           of
           the
           Air
           ,
           as
           will
           hereafter
           appear
           .
        
         
           But
           ,
           to
           the
           end
           that
           we
           may
           not
           be
           in
           the
           dark
           ,
           as
           to
           the
           true
           Nature
           of
           this
           Difficulty
           ,
           I
           affirm
           that
           it
           chiefly
           proceeds
           from
           the
           exceeding
           niceness
           of
           rectifying
           the
           Bob
           exactly
           ,
           when
           you
           have
           already
           brought
           the
           Clock
           to
           go
           pretty
           near
           the
           true
           Time
           ;
           as
           suppose
           ,
           for
           example
           ,
           that
           a
           Royal
           Pendulum
           were
           so
           well
           rectified
           ,
           that
           being
           kept
           going
           the
           whole
           Year
           round
           ,
           it
           should
           be
           just
           at
           the
           same
           Day
           Twelve
           Month
           but
           6′
           5″
           too
           slow
           for
           the
           Sun
           ,
           which
           some
           perhaps
           will
           account
           a
           great
           matter
           ;
           
           now
           this
           turn'd
           all
           into
           Seconds
           makes
           just
           365
           ,
           and
           by
           consequence
           the
           Clock
           has
           gone
           each
           Day
           but
           a
           Second
           of
           Time
           too
           slow
           .
        
         
           Now
           ,
           by
           the
           following
           Table
           of
           Pendulums
           ,
           we
           find
           that
           a
           Royal
           Pendulum
           41
           Inches
           long
           ,
           each
           Blow
           of
           which
           is
           a
           Second
           of
           Time
           ,
           strikes
           just
           3600
           Blows
           in
           an
           Hour
           :
           Now
           this
           Pendulum
           will
           go
           faster
           by
           45
           Blows
           in
           an
           Hour
           ,
           if
           screw'd
           up
           an
           Inch
           shorter
           ,
           which
           is
           faster
           in
           a
           Day
           near
           1080
           Seconds
           ;
           now
           if
           an
           Inch
           shorter
           makes
           a
           Pendulum
           go
           near
           1080
           Seconds
           in
           a
           Day
           faster
           't
           will
           then
           require
           the
           Bob
           to
           be
           screwed
           up
           but
           the
           thousand
           and
           eigtieth
           part
           of
           an
           Inch
           to
           make
           it
           go
           in
           a
           Day
           but
           one
           Second
           faster
           ,
           or
           so
           much
           as
           the
           Clock
           is
           said
           to
           have
           lost
           ;
           which
           is
           so
           very
           small
           a
           matter
           that
           no
           Man
           living
           can
           by
           guess
           hit
           it
           exactly
           ,
           the
           least
           Turn
           that
           shall
           be
           given
           it
           may
           perhaps
           make
           it
           go
           ten
           Times
           as
           much
           too
           fast
           as
           it
           before
           went
           too
           slow
           .
        
         
           Now
           to
           the
           end
           that
           this
           may
           ,
           if
           possible
           ,
           be
           done
           by
           some
           more
           certain
           Rule
           &
           Method
           than
           any
           yet
           commonly
           known
           ,
           I
           will
           here
           make
           bold
           to
           propose
           a
           way
           
           by
           which
           this
           may
           be
           performed
           more
           exactly
           than
           heretofore
           ,
           and
           by
           which
           you
           may
           make
           a
           near
           Estimation
           how
           much
           a
           Royal
           Pendulum
           that
           strikes
           Seconds
           (
           for
           this
           sort
           only
           is
           here
           intended
           )
           ought
           to
           be
           made
           shorter
           or
           longer
           ,
           to
           go
           faster
           or
           slower
           a
           Second
           in
           a
           Day
           ,
           and
           the
           same
           Rule
           by
           which
           you
           know
           how
           to
           alter
           it
           one
           Second
           will
           direct
           you
           how
           to
           alter
           it
           2
           or
           3
           ,
           or
           more
           if
           occasion
           require
           it
           .
        
         
           By
           the
           forementioned
           Table
           of
           Pendulums
           ,
           we
           find
           that
           a
           41
           Inch
           Pendulum
           goes
           45
           Blows
           (
           which
           are
           all
           nearly
           Seconds
           )
           in
           an
           Hour
           faster
           ,
           if
           screwed
           up
           an
           Inch
           higher
           ;
           and
           being
           let
           down
           an
           inch
           longer
           ;
           it
           then
           goes
           43
           Blows
           slower
           ,
           that
           is
           ,
           strikes
           so
           many
           Blows
           less
           in
           an
           Hour
           ;
           now
           if
           between
           these
           2
           Numbers
           we
           take
           a
           mean
           one
           ,
           which
           is
           44
           ,
           't
           will
           be
           suitable
           to
           the
           Lengths
           near
           41
           Inches
           ,
           for
           so
           many
           Blows
           will
           a
           Pendulum
           39
           and
           an
           half
           strike
           more
           than
           one
           of
           41
           Inches
           and
           an
           half
           long
           :
           Now
           44
           difference
           in
           an
           Hour
           makes
           in
           a
           Day
           1056.
           divide
           this
           number
           1056
           by
           the
           number
           of
           Turns
           which
           the
           Screw
           of
           your
           Pendulum
           makes
           in
           an
           Inch
           ,
           
           and
           the
           Quotient
           shall
           be
           the
           Number
           ,
           into
           which
           the
           Nut
           of
           that
           Screw
           must
           be
           divided
           ;
           now
           one
           of
           these
           Divisions
           turned
           about
           shall
           alter
           the
           Motion
           of
           that
           Pendulum
           a
           Second
           in
           a
           Day
           .
        
         
           But
           to
           avoid
           the
           Trouble
           of
           thus
           dividing
           ,
           I
           have
           here
           added
           a
           Table
           ,
           by
           which
           ,
           knowing
           the
           Turns
           your
           Screw
           makes
           in
           an
           Inch
           ,
           you
           may
           ,
           by
           Inspection
           only
           know
           how
           to
           divide
           the
           Nut
           that
           belongs
           thereunto
           ,
           the
           Table
           reaches
           from
           15
           Threds
           or
           Turns
           of
           the
           Screw
           in
           an
           Inch
           to
           40
           ,
           within
           which
           Numbers
           ,
           I
           suppose
           ,
           all
           Screws
           will
           be
           comprehended
           ,
           that
           belong
           to
           Pendulums
           that
           strike
           Seconds
           .
        
         
         
         
         
         
         
         
         
         
         
         
         
         
           
             
             The
             Table
             for
             dividing
             the
             Nut
             of
             a
             Pendulum
             Screw
             .
          
           
             
               
                 
                   Turns
                
                 
                   Divisions
                
              
               
                 
                   15
                
                 
                   70
                
              
               
                 
                   16
                
                 
                   66
                
              
               
                 
                   17
                
                 
                   62
                
              
               
                 
                   18
                
                 
                   58
                
              
               
                 
                   19
                
                 
                   55
                
              
               
                 
                   20
                
                 
                   52
                
              
               
                 
                   21
                
                 
                   50
                
              
               
                 
                   22
                
                 
                   48
                
              
               
                 
                   23
                
                 
                   45
                
              
               
                 
                   24
                
                 
                   44
                
              
               
                 
                   25
                
                 
                   42
                
              
               
                 
                   26
                
                 
                   40
                
              
               
                 
                   27
                
                 
                   39
                
              
               
                 
                   28
                
                 
                   37
                
              
               
                 
                   29
                
                 
                   36
                
              
               
                 
                   30
                
                 
                   35
                
              
               
                 
                   31
                
                 
                   34
                
              
               
                 
                   32
                
                 
                   33
                
              
               
                 
                   33
                
                 
                   32
                
              
               
                 
                   34
                
                 
                   31
                
              
               
                 
                   35
                
                 
                   30
                
              
               
                 
                   36
                
                 
                   29
                
              
               
                 
                   37
                
                 
                   28
                
              
               
                 
                   38
                
                 
                   27
                
              
               
                 
                   39
                
                 
                   26
                
              
               
                 
                   40
                
                 
                   25
                
              
            
          
        
         
           
           
             The
             Uses
             of
             the
             Table
             for
             dividing
             the
             Nut
             of
             a
             Pendulum
             Screw
             .
          
           
             Find
             out
             how
             many
             Threds
             or
             Turns
             of
             your
             Screw
             are
             contained
             in
             an
             Inch
             ,
             by
             applying
             the
             Inch-Division
             of
             a
             Rule
             thereunto
             ,
             which
             number
             of
             Turns
             seek
             out
             among
             the
             first
             Row
             of
             Figures
             on
             the
             Left
             Hand
             ,
             and
             against
             it
             ,
             in
             the
             second
             Row
             ,
             you
             have
             the
             Number
             that
             the
             Nut
             must
             be
             divided
             into
             that
             belongs
             to
             that
             Screw
             :
             Now
             the
             Nut
             ,
             turn'd
             about
             but
             one
             of
             these
             Divisions
             ,
             will
             alter
             the
             Clocks
             Motion
             a
             Second
             in
             a
             Day
             ;
             so
             that
             let
             the
             Screw
             be
             finer
             or
             courser
             ,
             yet
             by
             this
             Table
             you
             may
             readily
             know
             into
             how
             many
             Divisions
             its
             Nut
             must
             be
             divided
             .
             Note
             ,
             that
             if
             the
             Clock
             has
             got
             or
             lost
             in
             a
             Day
             above
             one
             Second
             ,
             then
             you
             must
             turn
             the
             Nut
             about
             so
             many
             Divisions
             ;
             as
             if
             it
             have
             lost
             in
             60
             Days
             4
             Minutes
             ,
             which
             is
             4
             Seconds
             in
             a
             Day
             ,
             turn
             it
             then
             upwards
             4
             Divisions
             ,
             and
             that
             will
             make
             it
             go
             4
             Seconds
             in
             a
             Day
             faster
             ,
             or
             so
             much
             Time
             as
             it
             had
             gone
             too
             slow
             :
             And
             the
             like
             must
             be
             done
             for
             any
             other
             Number
             lost
             or
             got
             .
          
           
           
             Now
             though
             this
             Rule
             be
             ten
             times
             more
             exact
             than
             any
             yet
             known
             ,
             yet
             for
             all
             that
             it
             may
             be
             yet
             found
             difficult
             to
             make
             a
             Clock
             go
             exact
             ,
             especially
             for
             a
             long
             time
             together
             ;
             for
             though
             a
             
               Royal
               Pendulum
            
             be
             the
             most
             excellent
             Contrivance
             in
             the
             World
             for
             exactness
             of
             keeping
             Time
             ,
             yet
             the
             different
             degrees
             of
             Rarity
             and
             Density
             in
             the
             Air
             ,
             does
             oftentimes
             alter
             the
             nature
             of
             the
             
               Pendulums
               motion
            
             ,
             a
             
               thick
               Air
            
             not
             suffering
             it
             to
             vibrate
             so
             freely
             ,
             nor
             so
             far
             as
             a
             
               thin
               Air
            
             does
             ;
             the
             Motion
             of
             the
             Pendulum
             may
             be
             also
             somewhat
             altered
             by
             the
             Oyl
             growing
             drier
             and
             thicker
             with
             which
             the
             Penets
             are
             moistned
             ;
             for
             when
             a
             Clock
             is
             clean
             ,
             and
             the
             Oyl
             thin
             and
             free
             from
             foulness
             ,
             the
             Pendulum
             plays
             differently
             from
             what
             it
             does
             when
             the
             Clock
             is
             foul
             ,
             and
             the
             Peuets
             dry
             and
             dirty
             :
             But
             here
             you
             are
             to
             note
             ,
             That
             not
             withstanding
             the
             
               Royal
               Pendulum
            
             is
             subject
             to
             be
             altered
             somewhat
             in
             its
             Motion
             by
             the
             aforesaid
             Causes
             ,
             that
             't
             is
             nothing
             in
             comparison
             to
             what
             happens
             in
             the
             common
             Crown-wheel
             Pendulum
             ,
             for
             these
             are
             apt
             to
             be
             varied
             ten
             times
             more
             than
             the
             other
             ,
             which
             still
             
             makes
             very
             much
             for
             the
             Reputation
             of
             the
             
               Royal
               Pendulum
            
             .
          
           
             Since
             then
             the
             Air
             ,
             and
             Oyl
             ,
             and
             Dust
             ,
             are
             apt
             to
             cause
             the
             best
             Clock
             to
             go
             less
             certain
             ,
             than
             it
             otherwise
             would
             ;
             I
             have
             thought
             fit
             to
             propose
             a
             way
             by
             which
             it
             may
             be
             known
             when
             any
             thing
             considerable
             of
             this
             nature
             happens
             ,
             and
             that
             is
             thus
             ,
             Screw
             or
             fasten
             to
             the
             back
             of
             the
             Case
             a
             
               brass
               Plate
            
             ,
             with
             2
             sliding
             Indexes
             fitted
             to
             it
             ,
             that
             may
             be
             set
             exactly
             to
             the
             Compass
             which
             your
             Pendulum
             fetches
             ,
             and
             by
             that
             you
             may
             perceive
             whether
             your
             Pendulum
             alters
             in
             its
             Compass
             ,
             for
             should
             it
             do
             so
             in
             the
             time
             of
             your
             adjusting
             of
             it
             ,
             you
             will
             find
             it
             a
             very
             hard
             matter
             to
             rectifie
             it
             well
             ;
             and
             if
             nothing
             of
             this
             happens
             till
             it
             be
             brought
             to
             go
             compleatly
             true
             ,
             yet
             if
             the
             Compass
             of
             your
             Pendulum
             does
             afterwards
             differ
             ,
             you
             will
             certainly
             find
             it
             not
             to
             keep
             the
             same
             time
             it
             did
             when
             first
             adjusted
             ,
             and
             the
             best
             Clocks
             that
             are
             will
             sometimes
             be
             subject
             to
             these
             unavoidable
             Accidents
             .
          
           
             But
             although
             those
             little
             Irregularities
             in
             the
             Motion
             of
             a
             good
             Pendulum
             ,
             may
             sometimes
             happen
             and
             prove
             some
             hindrance
             
             to
             the
             exactness
             of
             its
             Motion
             ,
             yet
             when
             you
             come
             to
             know
             how
             much
             it
             varies
             from
             the
             truth
             ,
             you
             may
             soon
             correct
             it
             by
             the
             foregoing
             Rules
             ,
             if
             you
             see
             occasion
             .
             Indeed
             a
             constant
             Inclination
             to
             go
             either
             too
             fast
             ,
             or
             too
             slow
             ,
             argues
             rather
             a
             not
             being
             well
             adjusted
             at
             first
             ,
             for
             if
             it
             vary
             from
             the
             Influence
             of
             the
             Air
             ,
             that
             aptness
             to
             go
             false
             will
             continue
             no
             longer
             when
             the
             temper
             of
             the
             Air
             returns
             to
             its
             former
             state
             ,
             and
             then
             the
             Clock
             will
             return
             to
             its
             old
             pitch
             of
             Motion
             ;
             but
             if
             it
             happen
             through
             foulness
             (
             which
             may
             be
             guest
             at
             by
             its
             having
             gone
             true
             a
             long
             time
             before
             )
             then
             't
             will
             continue
             to
             go
             Irregular
             till
             the
             Clock
             be
             made
             clean
             ,
             new
             oyl'd
             ,
             and
             put
             in
             order
             :
             But
             when
             all
             is
             said
             that
             can
             be
             said
             on
             this
             matter
             ,
             if
             the
             Clock
             be
             a
             well
             made
             Piece
             of
             Work
             ,
             all
             these
             Alterations
             in
             the
             Motions
             will
             be
             so
             inconsiderable
             ,
             as
             not
             to
             be
             worth
             the
             noting
             ,
             if
             you
             observe
             constantly
             to
             set
             it
             according
             to
             the
             Design
             of
             the
             
               Second
               Table
            
             ,
             and
             Correct
             it
             once
             or
             twice
             a
             Year
             by
             the
             Sun.
             but
             for
             base
             and
             
               ill
               Work
            
             ,
             no
             Art
             of
             Man
             can
             make
             that
             go
             exactly
             and
             well
             one
             Quarter
             of
             the
             time
             that
             the
             other
             will.
             
          
           
           
             From
             all
             that
             has
             been
             spoken
             hitherto
             concerning
             the
             
               Royal
               Pendulum
            
             ,
             we
             may
             gather
             that
             the
             same
             Exactness
             of
             keeping
             Time
             ,
             is
             not
             to
             be
             expected
             in
             short
             
               Crown-wheel
               Pendulums
            
             ;
             Indeed
             if
             fuch
             are
             
               good
               Work
            
             ,
             they
             may
             be
             made
             to
             go
             very
             well
             ,
             but
             yet
             not
             so
             exactly
             as
             the
             
               Royal
               Pendulum
            
             ;
             for
             the
             shorter
             the
             Pendulum
             is
             ,
             the
             more
             difficult
             it
             is
             to
             adjust
             it
             exactly
             :
             And
             when
             the
             adjusting
             part
             is
             done
             never
             so
             true
             ,
             yet
             the
             uncertainty
             that
             this
             kind
             of
             Pendulum
             is
             subject
             to
             in
             the
             Compass
             it
             fetches
             ,
             will
             not
             suffer
             it
             to
             keep
             so
             equal
             a
             Time
             ,
             as
             the
             
               Royal
               Pendulum
            
             ;
             the
             different
             Temper
             of
             the
             Weather
             will
             alter
             it
             very
             considerably
             ,
             if
             compared
             with
             the
             other
             ;
             and
             't
             will
             also
             be
             sooner
             out
             of
             order
             in
             the
             going
             ,
             from
             the
             foulness
             and
             thickness
             of
             the
             Oyl
             that
             the
             Penuets
             are
             moistned
             with
             .
          
           
             The
             best
             and
             easiest
             way
             to
             adjust
             such
             a
             Clock
             as
             this
             ,
             is
             by
             a
             
               Royal
               Pendulum
            
             already
             Rectified
             ,
             for
             a
             Standard
             to
             Adjust
             other
             Clocks
             by
             ;
             for
             when
             by
             that
             you
             have
             brought
             a
             short
             
               Crown-wheel
               Pendulum
            
             ,
             (
             of
             which
             sort
             all
             Spring-Clocks
             are
             for
             the
             most
             part
             )
             
             pretty
             near
             to
             the
             Truth
             ,
             take
             exact
             notice
             how
             much
             it
             differs
             from
             it
             in
             either
             one
             Day
             or
             two
             Days
             ,
             as
             you
             please
             ;
             then
             give
             the
             Bob
             just
             a
             whole
             turn
             about
             upward
             ,
             if
             it
             go
             too
             slow
             ,
             or
             downward
             if
             it
             go
             too
             fast
             ;
             and
             see
             how
             much
             that
             Turn
             will
             make
             it
             differ
             from
             the
             Standard
             above
             what
             it
             did
             before
             in
             a
             Day
             ,
             or
             two
             Days
             time
             .
             Now
             knowing
             how
             many
             Seconds
             in
             a
             Day
             a
             Turn
             of
             the
             Bob
             will
             alter
             ,
             you
             may
             soon
             bring
             it
             to
             keep
             
               true
               time
            
             ,
             by
             turning
             it
             so
             many
             Turns
             or
             parts
             of
             a
             
               Turn
               about
            
             ,
             as
             shall
             answer
             the
             Time
             it
             has
             gone
             too
             fast
             ,
             or
             too
             slow
             .
          
           
             As
             for
             those
             Pocket-Watches
             which
             are
             now
             so
             improperly
             called
             Pendulums
             ,
             there
             is
             less
             to
             be
             expected
             from
             them
             than
             from
             a
             
               Crown-wheel
               Pendulum
            
             ;
             for
             though
             this
             
               delicate
               Invention
            
             of
             the
             Ingenious
             Mr.
             
               Robert
               Hook
            
             does
             strangely
             Rectifie
             the
             Motion
             of
             the
             Balance
             ,
             yet
             must
             it
             not
             compare
             with
             either
             of
             the
             other
             ,
             as
             to
             the
             Truth
             of
             going
             ,
             for
             't
             is
             the
             hardest
             thing
             in
             the
             World
             to
             make
             a
             Watch
             keep
             the
             same
             Time
             ,
             when
             laid
             on
             what
             part
             or
             side
             soever
             ,
             you
             will
             be
             pleas'd
             to
             turn
             it
             ,
             which
             rightly
             considered
             ,
             
             may
             reasonably
             obtain
             for
             them
             some
             grains
             of
             allowance
             :
             All
             that
             I
             shall
             add
             more
             ,
             is
             ,
             that
             if
             you
             know
             but
             nearly
             how
             much
             the
             turning
             of
             each
             Division
             on
             the
             
               Justning
               Plate
            
             will
             make
             it
             go
             either
             faster
             or
             slower
             ,
             you
             may
             then
             at
             any
             time
             with
             greater
             certainty
             ,
             adjust
             it
             to
             a
             
               Standard
               Pendulum
            
             ;
             and
             this
             any
             one
             may
             attain
             to
             with
             but
             the
             trouble
             of
             a
             little
             Observation
             ;
             for
             if
             the
             Watch
             ,
             for
             example
             ,
             have
             gone
             too
             slow
             two
             Minutes
             in
             a
             Day
             ,
             turn
             the
             
               Justning
               Plate
            
             about
             one
             Division
             faster
             ,
             and
             if
             that
             Division
             make
             it
             go
             four
             Minutes
             too
             fast
             ,
             in
             stead
             of
             the
             two
             ,
             which
             before
             it
             went
             too
             slow
             ,
             then
             conclude
             that
             that
             Division
             has
             altered
             it
             in
             a
             Day
             six
             Minutes
             ;
             and
             by
             consequence
             if
             you
             turn
             it
             
               two
               thirds
            
             back
             ,
             it
             will
             make
             the
             Watch
             go
             right
             as
             it
             ought
             to
             do
             .
          
           
             I
             shall
             only
             add
             one
             more
             Note
             concerning
             
               Spring
               Clocks
            
             ,
             or
             those
             that
             go
             with
             
               Crown-wheel
               Pendulums
            
             ;
             and
             that
             is
             ,
             that
             although
             as
             yet
             they
             have
             not
             been
             capable
             of
             keeping
             so
             exact
             a
             Time
             as
             the
             
               Royal
               Pendulum
            
             ,
             yet
             if
             the
             Pendulum
             of
             a
             Spring-Clock
             instead
             of
             playing
             upon
             
             
             
             
             
             an
             edge
             ,
             as
             they
             now
             generally
             do
             ,
             were
             hung
             upon
             a
             String
             ,
             about
             two
             Inches
             long
             ,
             and
             that
             Spring
             were
             so
             filled
             according
             to
             the
             Rules
             of
             Art
             ,
             as
             that
             in
             the
             Pendulums
             vibration
             ,
             it
             might
             bend
             proportionable
             to
             the
             Cycloid
             ,
             its
             Center
             of
             Motion
             would
             then
             still
             shorten
             ,
             as
             the
             way
             of
             its
             vibration
             grows
             longer
             ;
             and
             by
             consequence
             the
             farther
             the
             Pendulum
             swings
             out
             ,
             the
             quicker
             would
             its
             return
             be
             ,
             and
             so
             all
             its
             vibrations
             whether
             longer
             or
             shorter
             ,
             would
             be
             performed
             in
             the
             same
             equal
             time
             ,
             and
             then
             its
             Motion
             would
             be
             much
             more
             steady
             than
             it
             is
             ,
             and
             be
             nearly
             as
             exact
             as
             that
             of
             a
             
               Royal
               Pendulum
            
             .
          
        
         
           
           
             The
             manner
             of
             Rightly
             fixing
             ,
             or
             Setting
             up
             Pendulums
             to
             go
             well
             .
          
           
             THE
             Difficulty
             of
             setting
             up
             
               Pendulum
               Clocks
            
             rightly
             in
             such
             places
             where
             the
             help
             of
             the
             
               Clock
               maker
            
             cannot
             be
             had
             ,
             is
             the
             Reason
             that
             many
             Gentlemen
             who
             live
             far
             off
             from
             London
             ,
             are
             as
             yet
             unfurnished
             with
             them
             ;
             and
             it
             also
             too
             often
             happens
             ,
             that
             Clocks
             who
             at
             first
             have
             been
             set
             up
             well
             as
             to
             matter
             of
             going
             ,
             have
             by
             accident
             been
             misplac'd
             or
             jumbl'd
             awry
             ,
             and
             so
             are
             made
             to
             stand
             still
             and
             become
             useless
             meerly
             for
             want
             of
             Skill
             in
             the
             Owner
             to
             put
             them
             again
             to
             rights
             ;
             in
             order
             therefore
             to
             Enable
             all
             Persons
             not
             only
             to
             Set
             a
             Pendulum
             Clock
             up
             Rightly
             ,
             but
             also
             to
             Reduce
             him
             again
             to
             rights
             ,
             when
             by
             accident
             he
             is
             misplac'd
             ,
             I
             have
             here
             made
             publick
             the
             following
             Directions
             .
          
           
           
             First
             ,
             Let
             the
             Workman
             ,
             by
             whose
             Hands
             the
             Clock
             is
             made
             ,
             set
             him
             upright
             at
             home
             in
             his
             own
             House
             ,
             and
             there
             having
             made
             a
             through
             tryal
             of
             his
             going
             ,
             let
             him
             then
             stop
             the
             Pendulum
             ,
             and
             when
             't
             is
             perfectly
             at
             rest
             ,
             let
             him
             fix
             or
             drive
             into
             the
             back
             of
             the
             Case
             a
             strong
             Stud
             of
             Brass
             or
             Iron
             ,
             with
             the
             end
             turn'd
             a
             little
             up
             ,
             which
             he
             must
             place
             so
             as
             that
             the
             Beak
             that
             turns
             up
             may
             stand
             exactly
             under
             the
             lower
             end
             of
             the
             Pendulum
             Rod
             ;
             and
             this
             will
             sufficiently
             direct
             you
             how
             to
             Set
             him
             up
             in
             any
             other
             Place
             :
             For
             when
             the
             Clock
             is
             to
             be
             Set
             up
             by
             him
             that
             buys
             him
             ;
             't
             is
             but
             placing
             the
             Case
             so
             that
             the
             end
             of
             the
             Pendulum
             Rod
             may
             hang
             just
             over
             the
             Beak
             of
             the
             Stud
             ,
             and
             then
             he
             will
             stand
             upright
             as
             he
             did
             before
             in
             then
             Workman's
             Hands
             .
          
           
             But
             in
             case
             this
             provision
             be
             not
             made
             ,
             then
             the
             Rule
             to
             do
             it
             by
             ,
             is
             this
             ;
             Set
             the
             Clock
             up
             in
             the
             place
             't
             is
             to
             stand
             in
             ,
             let
             the
             Pe●●ulum
             and
             the
             Pulleys
             which
             usually
             are
             fix'd
             to
             the
             Case
             be
             unfastned
             ,
             
             hang
             on
             the
             Weights
             ,
             and
             set
             the
             Pendulum
             a
             going
             ,
             by
             making
             of
             it
             swing
             between
             the
             Sides
             of
             the
             Case
             ;
             now
             if
             when
             the
             Clock
             is
             thus
             set
             a
             going
             ,
             you
             find
             the
             Pendulum
             to
             beat
             equally
             ,
             that
             is
             ,
             if
             there
             be
             the
             same
             Distance
             of
             Time
             between
             all
             its
             Blows
             ,
             which
             an
             attentive
             Ear
             will
             soon
             discover
             ;
             then
             does
             the
             Clock
             stand
             well
             ,
             and
             you
             must
             make
             him
             fast
             to
             the
             Place
             he
             stands
             against
             :
             But
             if
             you
             find
             one
             Blow
             Beat
             in
             less
             Time
             than
             the
             other
             ,
             then
             you
             must
             a
             little
             incline
             the
             Case
             to
             that
             Side
             which
             the
             Pendulum
             plays
             to
             ,
             when
             he
             strikes
             the
             shortest
             Blow
             ,
             and
             then
             you
             will
             find
             him
             to
             Beat
             more
             equal
             ;
             and
             when
             you
             have
             inclin'd
             the
             Case
             so
             much
             ,
             that
             you
             find
             exactly
             the
             same
             Distance
             of
             Time
             between
             the
             Blows
             or
             Vibrations
             ;
             then
             the
             Clock
             stands
             right
             for
             Going
             ,
             and
             you
             are
             to
             fix
             Him
             that
             He
             may
             stand
             firmly
             in
             that
             Posture
             .
          
           
             Now
             the
             Rule
             before
             given
             ,
             is
             general
             to
             all
             Pendulums
             ;
             for
             they
             all
             must
             
             stand
             so
             that
             the
             Beats
             of
             the
             Pendulum
             may
             be
             equally
             distant
             as
             to
             length
             of
             Time
             ,
             for
             otherwise
             if
             they
             stand
             awry
             ,
             so
             that
             one
             Blow
             ,
             or
             Vibration
             of
             the
             Pendulum
             is
             struck
             in
             less
             time
             than
             the
             other
             ,
             that
             Pendulum
             upon
             the
             least
             accident
             that
             shall
             happen
             ,
             will
             be
             apt
             to
             stand
             still
             ;
             and
             therefore
             great
             Care
             ought
             to
             be
             taken
             ,
             that
             not
             only
             
               Royal
               Pendulums
            
             ,
             but
             also
             
               Spring
               Clocks
            
             be
             set
             up
             exactly
             upright
             in
             the
             Places
             that
             they
             are
             ,
             to
             stand
             in
             ,
             and
             they
             never
             stand
             upright
             as
             they
             should
             do
             ,
             unless
             the
             Blows
             of
             the
             Pendulum
             beat
             equally
             .
          
           
             Note
             ,
             That
             as
             a
             long
             Swing-Clock
             ought
             to
             stand
             so
             as
             that
             the
             Pendulum
             beat
             equally
             ,
             so
             he
             must
             stand
             so
             as
             that
             the
             Pendulum
             play
             free
             from
             the
             back
             of
             the
             Case
             ,
             for
             if
             it
             stand
             right
             ,
             in
             this
             respect
             the
             Rod
             of
             the
             Pendulum
             will
             all
             the
             way
             up
             ,
             be
             parallel
             or
             equidistant
             from
             the
             back-part
             .
          
           
           
             Moreover
             ,
             take
             Care
             that
             the
             Clock
             be
             fix'd
             fast
             and
             firm
             ,
             that
             no
             Violence
             may
             justle
             Him
             out
             of
             his
             Place
             ;
             but
             if
             by
             Accident
             it
             should
             so
             come
             to
             pass
             ,
             you
             must
             then
             set
             Him
             again
             to
             Rights
             by
             the
             Rule
             before
             given
             from
             the
             exact
             beating
             of
             the
             Pendulum
             .
          
        
         
           
           
             A
             Table
             of
             Crown-Wheel'd
             Pendulums
             ,
             shewing
             the
             number
             of
             Beats
             made
             in
             an
             Hour
             ,
             by
             any
             length
             of
             Inches
             and
             Quarters
             ,
             from
             One
             Inch
             to
             Twelve
             ,
             the
             Bob
             about
             an
             Ounce
             in
             Weight
             .
          
           
             
               
                 
                   Inches
                
                 
                   Beats
                
              
               
                 
                   1
                   —
                   22946
                
              
               
                 
                   1
                
                 
                   20524
                
              
               
                 
                   2
                
                 
                   18735
                
              
               
                 
                   3
                
                 
                   17345
                
              
               
                 
                   2
                   —
                   16225
                
              
               
                 
                   1
                
                 
                   15298
                
              
               
                 
                   2
                
                 
                   18735
                
              
               
                 
                   3
                
                 
                   13837
                
              
               
                 
                   3
                   —
                   13248
                
              
               
                 
                   1
                
                 
                   12732
                
              
               
                 
                   2
                
                 
                   12265
                
              
               
                 
                   3
                
                 
                   11852
                
              
               
                 
                   4
                   —
                   11473
                
              
               
                 
                   1
                
                 
                   11131
                
              
               
                 
                   2
                
                 
                   10817
                
              
               
                 
                   3
                
                 
                   10528
                
              
               
                 
                   5
                   —
                   10262
                
              
               
                 
                   1
                
                 
                   10014
                
              
               
                 
                   2
                
                 
                   9781
                
              
               
                 
                   3
                
                 
                   9569
                
              
               
                 
                   6
                   —
                   9368
                
              
               
                 
                   1
                
                 
                   9178
                
              
               
                 
                   2
                
                 
                   9000
                
              
               
                 
                   3
                
                 
                   8832
                
              
               
                 
                   7
                   —
                   8672
                
              
               
                 
                   1
                
                 
                   8524
                
              
               
                 
                   2
                
                 
                   8381
                
              
               
                 
                   3
                
                 
                   8242
                
              
               
                 
                   8
                   —
                   8107
                
              
               
                 
                   1
                
                 
                   7989
                
              
               
                 
                   2
                
                 
                   7870
                
              
               
                 
                   3
                
                 
                   7764
                
              
               
                 
                   9
                   —
                   7653
                
              
               
                 
                   1
                
                 
                   7544
                
              
               
                 
                   2
                
                 
                   7448
                
              
               
                 
                   3
                
                 
                   7349
                
              
               
                 
                   10
                   —
                   7256
                
              
               
                 
                   1
                
                 
                   7167
                
              
               
                 
                   2
                
                 
                   7081
                
              
               
                 
                   3
                
                 
                   6998
                
              
               
                 
                   11
                   —
                   6919
                
              
               
                 
                   1
                
                 
                   6842
                
              
               
                 
                   2
                
                 
                   6767
                
              
               
                 
                   3
                
                 
                   6694
                
              
               
                 
                   12
                   —
                   6623
                
              
               
                 
                   1
                
                 
                   6565
                
              
               
                 
                   2
                
                 
                   6497
                
              
               
                 
                   3
                
                 
                   6431
                
              
            
          
           
           
             The
             first
             Row
             of
             Figures
             are
             Inches
             ,
             the
             second
             are
             Quarters
             of
             Inches
             ;
             the
             Figures
             against
             each
             of
             these
             are
             the
             Beats
             that
             a
             Pendulum
             of
             that
             length
             make
             in
             an
             Hour
             :
             For
             example
             ,
             2
             Inches
             beats
             16225
             Blows
             in
             an
             Hour
             ;
             and
             3
             Inches
             and
             a
             half
             beats
             12265
             ;
             and
             6
             Inches
             3
             quarters
             beats
             8832
             :
             Divide
             any
             of
             these
             Numbers
             by
             60
             ,
             and
             it
             shews
             you
             the
             Beats
             made
             in
             a
             Minute
             ,
             multiply
             any
             of
             these
             by
             24
             ,
             and
             it
             shews
             you
             the
             Beats
             made
             in
             a
             Day
             .
          
        
         
           
           
             A
             Table
             of
             Royal
             Pendulums
             ,
             shewing
             what
             Beats
             any
             Length
             makes
             in
             an
             Hour
             from
             12
             to
             60
             Inches
             ,
             the
             Bob
             2
             Pound
             Weight
             or
             more
             .
          
           
             
               
                 
                   Inches
                
                 
                   Beats
                
              
               
                 
                   12
                
                 
                   6651
                
              
               
                 
                   13
                
                 
                   6393
                
              
               
                 
                   14
                
                 
                   6161
                
              
               
                 
                   15
                
                 
                   5955
                
              
               
                 
                   16
                
                 
                   5765
                
              
               
                 
                   17
                
                 
                   5591
                
              
               
                 
                   18
                
                 
                   5433
                
              
               
                 
                   19
                
                 
                   5288
                
              
               
                 
                   20
                
                 
                   5154
                
              
               
                 
                   21
                
                 
                   5030
                
              
               
                 
                   22
                
                 
                   4915
                
              
               
                 
                   23
                
                 
                   4807
                
              
               
                 
                   24
                
                 
                   4706
                
              
               
                 
                   25
                
                 
                   4610
                
              
               
                 
                   26
                
                 
                   4522
                
              
               
                 
                   27
                
                 
                   4437
                
              
               
                 
                   28
                
                 
                   4356
                
              
               
                 
                   29
                
                 
                   4281
                
              
               
                 
                   30
                
                 
                   4209
                
              
               
                 
                   31
                
                 
                   4141
                
              
               
                 
                   32
                
                 
                   4075
                
              
               
                 
                   33
                
                 
                   4013
                
              
               
                 
                   34
                
                 
                   3953
                
              
               
                 
                   35
                
                 
                   3897
                
              
               
                 
                   36
                
                 
                   3843
                
              
               
                 
                   37
                
                 
                   3790
                
              
               
                 
                   38
                
                 
                   3793
                
              
               
                 
                   39
                
                 
                   3691
                
              
               
                 
                   40
                
                 
                   3645
                
              
               
                 
                   41
                
                 
                   3600
                
              
               
                 
                   42
                
                 
                   3557
                
              
               
                 
                   43
                
                 
                   3515
                
              
               
                 
                   44
                
                 
                   3475
                
              
               
                 
                   45
                
                 
                   3436
                
              
               
                 
                   46
                
                 
                   3399
                
              
               
                 
                   47
                
                 
                   3362
                
              
               
                 
                   48
                
                 
                   3327
                
              
               
                 
                   49
                
                 
                   3293
                
              
               
                 
                   50
                
                 
                   3260
                
              
               
                 
                   51
                
                 
                   3228
                
              
               
                 
                   52
                
                 
                   3196
                
              
               
                 
                   53
                
                 
                   3166
                
              
               
                 
                   54
                
                 
                   3137
                
              
               
                 
                   55
                
                 
                   3108
                
              
               
                 
                   56
                
                 
                   3080
                
              
               
                 
                   57
                
                 
                   3053
                
              
               
                 
                   58
                
                 
                   3027
                
              
               
                 
                   59
                
                 
                   3001
                
              
               
                 
                   60
                
                 
                   2976
                
              
               
                 
                   61
                
                 
                   2951
                
              
               
                 
                   62
                
                 
                   2927
                
              
               
                 
                   63
                
                 
                   2904
                
              
               
                 
                   64
                
                 
                   2880
                
              
               
                 
                   65
                
                 
                   2859
                
              
            
          
           
           
             In
             this
             Table
             ,
             the
             first
             Row
             of
             Figures
             ,
             in
             each
             Colume
             ,
             are
             the
             Inches
             of
             a
             Pendulum's
             Length
             :
             The
             second
             Row
             are
             the
             Beats
             that
             a
             Pendulum
             of
             that
             Length
             makes
             in
             an
             Hour
             .
             Thus
             one
             of
             41
             Inches
             long
             beats
             3600
             times
             ,
             and
             one
             of
             64
             2880.
             
          
        
         
           
           
             The
             Table
             of
             Royal
             Pendulums
             continued
             ,
             from
             3
             Foot
             long
             to
             30
             ,
             for
             the
             Use
             of
             such
             as
             make
             Church
             and
             Turret-Clocks
             .
          
           
             
               
                 
                   Feet
                
                 
                   Beats
                
              
               
                 
                   3
                
                 
                   3842
                
              
               
                 
                   4
                
                 
                   3327
                
              
               
                 
                   5
                
                 
                   2976
                
              
               
                 
                   6
                
                 
                   2716
                
              
               
                 
                   7
                
                 
                   2515
                
              
               
                 
                   8
                
                 
                   2353
                
              
               
                 
                   9
                
                 
                   2218
                
              
               
                 
                   10
                
                 
                   2104
                
              
               
                 
                   11
                
                 
                   2006
                
              
               
                 
                   12
                
                 
                   1912
                
              
               
                 
                   13
                
                 
                   1845
                
              
               
                 
                   14
                
                 
                   1778
                
              
               
                 
                   15
                
                 
                   1718
                
              
               
                 
                   16
                
                 
                   1664
                
              
               
                 
                   17
                
                 
                   1614
                
              
               
                 
                   18
                
                 
                   1568
                
              
               
                 
                   19
                
                 
                   1526
                
              
               
                 
                   20
                
                 
                   1488
                
              
               
                 
                   21
                
                 
                   1452
                
              
               
                 
                   22
                
                 
                   1429
                
              
               
                 
                   23
                
                 
                   1387
                
              
               
                 
                   24
                
                 
                   1353
                
              
               
                 
                   25
                
                 
                   1331
                
              
               
                 
                   26
                
                 
                   1305
                
              
               
                 
                   27
                
                 
                   1288
                
              
               
                 
                   28
                
                 
                   1257
                
              
               
                 
                   29
                
                 
                   1235
                
              
               
                 
                   30
                
                 
                   1215
                
              
            
          
           
           
             In
             this
             Table
             ,
             the
             first
             Row
             of
             Figures
             are
             the
             Feet
             of
             any
             Pendulum's
             Length
             ,
             the
             second
             Row
             are
             the
             Beats
             that
             that
             Length
             makes
             in
             an
             Hour
             ;
             as
             10
             Foot
             long
             beats
             2104
             in
             an
             Hour
             ,
             so
             a
             Pendulum
             of
             20
             Foot
             long
             beats
             1488
             Blows
             in
             an
             Hour
             .
          
           
             The
             foregoing
             Table
             of
             Pendulums
             I
             was
             ,
             in
             some
             measure
             necessitated
             to
             publish
             ,
             in
             order
             to
             demonstrate
             why
             heretofore
             it
             has
             been
             found
             so
             difficult
             to
             adjust
             a
             Clock
             to
             the
             Table
             of
             Equations
             .
             But
             ,
             besides
             this
             ,
             I
             thought
             it
             might
             be
             of
             good
             Use
             to
             some
             ,
             who
             ,
             in
             contriving
             Numbers
             for
             new
             Clocks
             ,
             or
             for
             old
             Clocks
             altered
             into
             Pendulums
             ,
             are
             often
             at
             a
             loss
             what
             Length
             of
             Pendulum
             to
             fit
             their
             Number
             to
             .
             Perhaps
             my
             so
             doing
             may
             anger
             some
             ,
             but
             the
             pleasuring
             of
             more
             will
             countervail
             that
             Mischief
             .
          
           
             The
             Table
             of
             Crown-Wheel'd
             Pendulums
             is
             calculated
             from
             a
             Standard
             of
             the
             same
             sort
             ,
             6
             Inches
             and
             a
             half
             long
             ,
             that
             strikes
             9000
             Blows
             in
             an
             Hour
             :
             And
             that
             of
             Royal
             Pendulums
             from
             one
             of
             
             41
             Inches
             ,
             that
             strikes
             Seconds
             ,
             or
             3600
             Blows
             in
             an
             Hour
             .
             In
             both
             the
             Tables
             you
             may
             perceive
             ,
             That
             a
             Pendulum
             that
             strikes
             but
             half
             so
             many
             Blows
             as
             another
             is
             four
             Times
             as
             long
             :
             This
             noted
             ,
             gives
             you
             a
             true
             insight
             into
             the
             Nature
             of
             the
             Pendulum
             .
             The
             Tables
             are
             exact
             ,
             as
             to
             their
             whole
             Numbers
             ,
             and
             would
             always
             give
             you
             the
             exact
             length
             ,
             did
             not
             different
             ways
             of
             making
             Clocks
             cause
             an
             Alteration
             ,
             insomuch
             that
             sometimes
             a
             Pendulum
             that
             strikes
             Seconds
             shall
             be
             above
             a
             quarter
             of
             an
             Inch
             longer
             than
             another
             shall
             ;
             we
             must
             bear
             with
             what
             we
             cannot
             avoid
             .
          
        
      
       
         
         
           The
           best
           Rules
           for
           the
           ORDERING
           and
           USE
           Both
           of
           the
           
             Quick-silver
             and
             Spirit
          
           WEATHER-GLASS
           .
        
         
           SInce
           't
           is
           so
           easy
           to
           be
           furnished
           in
           London
           with
           both
           these
           Sorts
           of
           Weather-Glasses
           ,
           I
           judge
           it
           needless
           ,
           now
           ,
           to
           give
           any
           Directions
           about
           their
           Making
           ;
           only
           thus
           much
           I
           shall
           take
           notice
           of
           ,
           That
           the
           Goodness
           of
           a
           Baroscope
           or
           Quick-silver
           Weather
           glass
           does
           consist
           wholly
           in
           the
           Largeness
           and
           Depth
           of
           the
           Cestern
           below
           ,
           and
           the
           Quantity
           of
           Quick-silver
           contained
           therein
           .
           Now
           ,
           that
           you
           may
           know
           whether
           a
           Cestern
           be
           large
           enough
           ,
           cause
           the
           
           Workman
           ,
           that
           makes
           it
           ,
           to
           fill
           the
           Tube
           about
           3
           Inches
           ,
           with
           part
           of
           the
           Mercury
           designed
           for
           its
           Use
           ;
           fill
           the
           Cestern
           with
           the
           best
           part
           of
           the
           rest
           that
           remains
           ,
           and
           then
           clapping
           across
           the
           Brims
           at
           the
           Cestern
           ,
           a
           Gage
           ,
           that
           shall
           have
           a
           Pin
           drove
           into
           it
           ,
           reaching
           just
           down
           to
           the
           Surface
           of
           the
           Mercury
           ,
           let
           the
           Mercury
           ,
           which
           before
           filled
           the
           3
           Inches
           of
           the
           Tube
           be
           put
           therein
           ;
           and
           if
           you
           find
           it
           not
           to
           raise
           the
           Mercury
           in
           the
           Cestern
           above
           the
           thickness
           of
           a
           Six
           Pence
           ,
           then
           is
           the
           Cestern
           of
           a
           sufficient
           Capacity
           .
        
         
           A
           Cestern
           of
           about
           2
           Inches
           and
           a
           half
           Diameter
           ,
           generally
           ,
           is
           large
           enough
           for
           any
           Tube
           ,
           that
           has
           not
           a
           Bore
           above
           a
           quarter
           of
           an
           Inch
           Diameter
           ,
           which
           is
           as
           large
           as
           is
           needful
           ;
           for
           if
           it
           be
           so
           large
           ,
           as
           that
           when
           the
           Quick-silver
           in
           the
           Glass
           ,
           by
           rising
           and
           falling
           ,
           do
           raise
           that
           in
           the
           Cestern
           too
           considerably
           ,
           then
           you
           will
           not
           constantly
           have
           that
           Distance
           between
           the
           Surface
           of
           the
           stagnant
           Mercury
           below
           and
           the
           numbred
           Figures
           on
           the
           Register
           Plates
           of
           the
           Weather-Glass
           ;
           for
           if
           the
           Glass
           be
           a
           good
           Glass
           ,
           measure
           that
           Distance
           when
           
           you
           will
           ,
           and
           you
           will
           always
           find
           it
           just
           28
           ,
           30
           or
           31
           Inches
           from
           the
           Divisions
           so
           numbred
           to
           the
           Superficies
           of
           the
           Quick-silver
           ,
           in
           the
           Cestern
           below
           .
        
         
           Note
           likewise
           ,
           That
           the
           End
           of
           the
           Tube
           ought
           to
           be
           emerst
           at
           least
           three
           quarters
           of
           an
           Inch
           within
           the
           Cestern
           of
           Quick-silver
           ,
           else
           the
           Air
           will
           be
           in
           danger
           of
           getting
           up
           into
           the
           Body
           of
           the
           Tube
           :
           For
           this
           reason
           there
           ought
           to
           be
           at
           least
           28
           Inches
           and
           3
           quarters
           Distance
           between
           the
           Figure
           28
           ,
           on
           the
           Register
           Plate
           and
           the
           Bottom
           of
           the
           Cestern
           .
        
         
           Now
           ,
           in
           order
           to
           set
           the
           Weather-glass
           up
           ,
           let
           the
           Frame
           be
           first
           fixed
           fast
           to
           the
           Place
           you
           design
           for
           it
           ;
           which
           is
           done
           by
           first
           driving
           therein
           a
           Nail
           or
           Tenter-hook
           ,
           fitted
           ,
           for
           that
           purpose
           ,
           upon
           which
           the
           Frame
           is
           to
           be
           hung
           or
           suspended
           ,
           and
           ,
           with
           a
           Screw
           ,
           let
           the
           Bottom
           thereof
           be
           firmly
           fastned
           to
           the
           Place
           ,
           or
           ,
           in
           want
           of
           a
           Screw
           ,
           by
           somewhat
           else
           that
           may
           perform
           the
           Work
           well
           .
        
         
           Then
           make
           the
           in
           side
           of
           the
           Glass
           Tube
           very
           clean
           and
           dry
           ,
           by
           means
           of
           a
           bright
           and
           clean
           piece
           of
           Wire
           ,
           made
           
           red
           hot
           at
           the
           End
           in
           a
           Fire
           ,
           and
           turned
           down
           for
           about
           half
           an
           Inch
           ,
           like
           the
           Eye
           of
           a
           Needle
           ,
           through
           which
           draw
           a
           long
           slip
           of
           fine
           softLawn
           Paper
           ,
           which
           I
           find
           best
           for
           this
           purpose
           ,
           because
           't
           is
           not
           apt
           to
           leave
           any
           Lint
           behind
           it
           ,
           as
           Linen
           Rags
           will
           ;
           which
           Lint
           will
           always
           cause
           a
           small
           Bleb
           of
           Air
           to
           remain
           round
           it
           ,
           so
           that
           in
           spite
           of
           all
           your
           Care
           and
           Pains
           you
           shall
           never
           obtain
           a
           perfect
           fine
           Cilender
           of
           Mercury
           .
        
         
           With
           this
           Paper
           ,
           in
           the
           Eye
           of
           the
           Wire
           ,
           let
           the
           Bore
           of
           the
           Tube
           be
           well
           cleansed
           ,
           by
           drawing
           of
           it
           to
           and
           fro
           ,
           from
           one
           End
           to
           the
           other
           ,
           till
           you
           are
           sure
           that
           you
           have
           not
           mist
           any
           Part
           thereof
           :
           And
           if
           you
           find
           ,
           when
           you
           have
           drawn
           it
           out
           ,
           that
           the
           Paper
           be
           any
           whit
           soiled
           ,
           put
           in
           a
           fresh
           Piece
           ,
           and
           after
           that
           another
           ,
           till
           you
           find
           the
           Paper
           come
           out
           as
           clean
           at
           it
           went
           in
           ,
           for
           should
           any
           Foulness
           or
           Moisture
           be
           left
           behind
           the
           Mercury
           will
           not
           play
           freely
           up
           and
           down
           .
        
         
           When
           you
           have
           cleansed
           the
           Tuble
           very
           well
           ,
           then
           prepare
           and
           make
           the
           Mercury
           fit
           to
           fill
           it
           with
           ,
           which
           you
           are
           to
           do
           in
           the
           manner
           following
           .
        
         
         
           Take
           an
           earthen
           Bason
           or
           Dish
           ,
           and
           put
           therein
           half
           a
           Sheet
           of
           clean
           white
           Paper
           ;
           then
           put
           the
           whole
           Quantity
           of
           Mercury
           which
           the
           maker
           of
           the
           Baroscope
           has
           fitted
           thereunto
           ,
           and
           having
           put
           it
           into
           a
           clean
           linen
           Cloath
           ,
           strain
           out
           gently
           so
           much
           of
           it
           as
           you
           judge
           will
           fill
           the
           Bore
           of
           the
           Tube
           and
           no
           more
           ,
           for
           should
           you
           twist
           and
           wring
           the
           Cloath
           ,
           the
           Quick
           silver
           is
           in
           ,
           to
           strain
           it
           all
           through
           ,
           you
           will
           ,
           in
           so
           doing
           ,
           find
           much
           Lint
           fall
           off
           from
           it
           ,
           and
           foul
           the
           Surface
           of
           the
           Mercury
           strain'd
           out
           ,
           so
           that
           you
           cannot
           fill
           the
           Tube
           with
           it
           without
           conveying
           some
           of
           the
           Lint
           along
           with
           it
           ,
           which
           will
           spoil
           the
           perfect
           smoothness
           of
           the
           Mercurial
           Cylender
           within
           the
           Glass
           .
        
         
           When
           you
           have
           purely
           strained
           out
           about
           one
           half
           of
           the
           Quick-silver
           ,
           take
           the
           Tube
           ,
           and
           resting
           the
           closed
           end
           in
           some
           large
           wooden
           or
           earthen
           Vessel
           ,
           to
           save
           the
           Mercury
           ,
           should
           any
           spill
           in
           the
           filling
           ;
           then
           graspe
           the
           open
           end
           of
           it
           between
           the
           Root
           of
           the
           Thumb
           and
           Fore-finger
           ,
           somewhat
           low
           ,
           that
           the
           hollowness
           between
           may
           serve
           instead
           of
           a
           Tunnel
           ;
           then
           fill
           the
           Tube
           with
           
           the
           pure
           clean-strain'd
           Quick-silver
           ,
           by
           by
           taking
           of
           it
           up
           with
           the
           clean
           Bowle-end
           of
           a
           Tobacco-Pipe
           ,
           or
           by
           putting
           of
           it
           into
           the
           Cestern-Glass
           ,
           first
           wiped
           clean
           ,
           and
           so
           pouring
           of
           it
           in
           till
           it
           be
           full
           ,
           within
           a
           quarter
           of
           an
           Inch
           of
           the
           Top
           of
           the
           Tube
           .
        
         
           Then
           ,
           to
           cleanse
           it
           from
           Air
           and
           Wind-Blebs
           ,
           stop
           the
           End
           with
           your
           Finger
           ,
           and
           raising
           the
           other
           End
           up
           ,
           somewhat
           above
           a
           Level
           ,
           let
           the
           Air
           ,
           included
           in
           the
           empty
           Space
           ,
           at
           the
           open
           End
           ,
           rise
           up
           very
           gently
           towards
           the
           Top
           or
           sealed
           End
           ,
           and
           this
           will
           take
           into
           it self
           all
           the
           other
           Blebs
           of
           Wind
           that
           lye
           in
           its
           Way
           ;
           and
           when
           this
           Bubble
           of
           Air
           is
           risen
           up
           quite
           to
           the
           End
           of
           the
           Tube
           ,
           let
           it
           return
           again
           ,
           by
           depressing
           a
           little
           that
           End
           which
           before
           was
           uppermost
           ,
           turning
           the
           Tube
           also
           ,
           at
           the
           same
           time
           ,
           that
           the
           Buble
           may
           take
           in
           its
           way
           all
           the
           Blebs
           of
           Wind
           that
           may
           yet
           remain
           on
           the
           other
           Sides
           of
           the
           Glass
           ;
           and
           ,
           thus
           ,
           by
           turning
           the
           Tube
           a
           little
           ,
           and
           making
           the
           Bubble
           pass
           and
           re-pass
           from
           one
           End
           to
           the
           other
           ,
           the
           Cylender
           of
           Quick-silver
           ,
           will
           be
           at
           last
           cleansed
           from
           all
           those
           little
           Blebs
           of
           Wind
           
           that
           appeared
           by
           the
           Sides
           of
           the
           Glass
           ,
           any
           of
           which
           ,
           should
           they
           remain
           in
           ,
           would
           in
           Time
           work
           themselves
           up
           into
           the
           Head
           of
           the
           Tube
           ,
           and
           be
           very
           injurious
           to
           the
           Quick-silvers
           true
           Motion
           .
        
         
           But
           if
           ,
           as
           I
           noted
           before
           ,
           the
           least
           Moisture
           or
           Lint
           be
           left
           in
           the
           Tube
           ,
           the
           greatest
           Care
           and
           Skill
           that
           can
           be
           used
           will
           not
           be
           able
           so
           perfectly
           to
           cleanse
           it
           from
           Air
           ,
           as
           not
           to
           leave
           the
           least
           Speck
           remaining
           :
           In
           which
           Case
           there
           is
           no
           Remedy
           but
           to
           empty
           the
           Tube
           and
           cleanse
           it
           a
           new
           ,
           according
           to
           the
           Method
           before
           prescribed
           .
           Note
           ,
           when
           the
           Tube
           is
           perfectly
           cleansed
           from
           Air
           ,
           then
           turn
           the
           open
           End
           up
           ,
           and
           fill
           it
           quite
           full
           with
           Quick-silver
           .
        
         
           Then
           Wipe
           the
           Cestern
           very
           clean
           ,
           and
           set
           it
           in
           its
           Place
           ,
           in
           the
           Cestern-Box
           ,
           then
           put
           therein
           all
           the
           remaining
           part
           of
           your
           Mercury
           ,
           which
           you
           need
           not
           take
           care
           to
           strain
           ,
           for
           Dust
           or
           Foulness
           in
           the
           Cestern
           signifies
           little
           ;
           then
           take
           the
           Glass
           Tube
           ,
           filled
           as
           before
           was
           taught
           ,
           and
           stopping
           the
           End
           of
           it
           with
           your
           Finger
           ,
           invert
           it
           so
           that
           you
           may
           immerge
           or
           put
           the
           End
           ,
           stopt
           with
           
           your
           Finger
           ,
           the
           more
           easily
           into
           the
           Cestern
           Mercury
           ,
           which
           ought
           to
           be
           done
           so
           that
           both
           Glass
           and
           Finger
           may
           touch
           the
           Cestern
           Bottom
           at
           the
           same
           time
           ,
           keeping
           the
           Tube
           in
           the
           mean
           while
           as
           near
           an
           upright
           as
           you
           can
           ,
           then
           of
           a
           suddain
           take
           away
           the
           Finger
           you
           stopt
           it
           with
           ,
           and
           as
           suddainly
           ,
           at
           the
           very
           same
           instant
           of
           Time
           raise
           the
           Tube
           just
           upright
           ,
           the
           which
           ,
           if
           you
           perform
           nimbly
           and
           well
           ,
           will
           be
           done
           before
           the
           Mercury
           in
           the
           Tube
           is
           all
           sunk
           down
           to
           its
           lowest
           station
           ,
           and
           so
           the
           Tube
           will
           be
           put
           up
           well
           ,
           without
           any
           admittance
           of
           outward
           Air.
           
        
         
           But
           in
           case
           any
           Air
           should
           get
           into
           the
           Tube
           ,
           in
           your
           attempting
           to
           set
           it
           up
           in
           its
           Place
           ,
           as
           sometimes
           happens
           ,
           then
           you
           must
           take
           it
           down
           again
           ,
           by
           getting
           your
           Finger
           under
           the
           open
           End
           ,
           to
           stop
           it
           ,
           before
           you
           lift
           it
           out
           of
           the
           Cestern
           Mercury
           ,
           and
           so
           repurge
           it
           of
           the
           Air
           got
           in
           ,
           according
           as
           you
           were
           taught
           in
           the
           foregoing
           Method
           ,
           and
           then
           try
           again
           to
           set
           it
           up
           well
           ;
           and
           if
           you
           should
           miss
           this
           second
           time
           ,
           then
           try
           a
           third
           ,
           for
           Experience
           will
           at
           length
           make
           you
           perfect
           .
        
         
         
           When
           the
           Tube
           is
           put
           up
           observe
           whether
           it
           stand
           well
           in
           the
           Cestern
           ,
           for
           some
           Cesterns
           are
           so
           ill
           plac'd
           that
           the
           Tube
           ,
           by
           reason
           of
           its
           being
           set
           too
           near
           the
           Side
           ,
           cannot
           be
           well
           surrounded
           by
           the
           Cestern
           Mercury
           ,
           by
           which
           means
           the
           Air
           will
           be
           apt
           to
           insinuate
           it self
           ,
           and
           get
           up
           into
           the
           Tube
           ,
           and
           spoil
           the
           
           Mercury's
           true
           Motion
           .
        
         
           If
           the
           Glass
           be
           already
           adjusted
           to
           your
           Hand
           by
           the
           Workman
           that
           made
           it
           ,
           you
           have
           then
           no
           more
           to
           do
           but
           to
           put
           into
           the
           Cestern
           all
           the
           Mercury
           that
           remains
           when
           the
           Tube
           is
           filled
           ;
           but
           in
           case
           the
           Glass
           be
           not
           already
           adjusted
           ,
           or
           that
           some
           part
           of
           the
           Quick-silver
           should
           be
           spilled
           or
           lost
           ,
           you
           must
           then
           provide
           to
           adjust
           it
           ,
           according
           as
           the
           Rules
           of
           Art
           require
           :
           Which
           is
           done
           thus
           ,
           Take
           a
           small
           streight
           Rod
           of
           Wood
           ,
           of
           the
           just
           length
           of
           28
           Inches
           ,
           this
           is
           generally
           called
           ,
           
             An
             adjusting
             Gage
          
           ,
           put
           one
           End
           of
           it
           into
           the
           Cestern
           ,
           and
           raise
           the
           other
           up
           till
           it
           touch
           the
           Division
           on
           the
           Register-Plate
           numbred
           with
           the
           Figure
           28
           ;
           then
           observe
           whether
           the
           Quick-silver
           in
           the
           Cestern
           does
           touch
           the
           other
           End
           ,
           if
           it
           does
           
           not
           ,
           you
           must
           put
           in
           more
           Mercury
           ,
           till
           it
           does
           ;
           but
           if
           the
           Mercury
           be
           already
           above
           the
           lower
           End
           of
           the
           Gage
           ,
           then
           you
           must
           ,
           with
           the
           clean
           Bowle-end
           of
           a
           Tobacco-Pipe
           take
           out
           so
           much
           of
           the
           Quick-silver
           as
           that
           that
           in
           the
           Cestern
           may
           but
           just
           touch
           the
           End
           of
           the
           Gage
           ,
           and
           then
           is
           the
           Glass
           compleatly
           and
           well
           adjusted
           .
        
         
           In
           case
           you
           have
           occasion
           to
           remove
           a
           Baroscope
           ,
           or
           Quick
           silver
           Weather-Glass
           ,
           out
           of
           one
           Room
           into
           another
           ,
           you
           need
           only
           loosen
           the
           Frame
           and
           take
           it
           from
           the
           Place
           to
           which
           it
           is
           fixt
           ,
           and
           so
           ,
           upright
           ,
           in
           the
           same
           Posture
           it
           stood
           in
           ,
           let
           it
           be
           carefully
           conveyed
           by
           Hand
           ,
           so
           gently
           ,
           and
           with
           a
           careful
           Step
           ,
           that
           the
           Quick
           silver
           may
           not
           surge
           over
           the
           Sides
           of
           the
           Cestern
           ,
           another
           Man
           ,
           in
           the
           mean
           Time
           ,
           making
           all
           things
           fit
           to
           set
           it
           up
           in
           its
           new
           Place
           ,
           according
           to
           the
           Directions
           before
           given
           for
           setting
           of
           a
           Weather-glass
           up
           .
        
         
           But
           here
           note
           ,
           That
           if
           the
           Baroscope
           be
           to
           be
           removed
           from
           one
           House
           to
           another
           ,
           it
           must
           be
           quite
           taken
           down
           :
           In
           doing
           which
           observe
           ,
           Frst
           ,
           To
           incline
           the
           Tube
           so
           low
           as
           it
           stands
           in
           the
           Cestern
           ,
           
           that
           the
           Quick-silver
           may
           rise
           up
           quite
           to
           the
           top
           ,
           then
           lift
           it
           out
           of
           the
           Cestern
           and
           let
           the
           Mercury
           run
           out
           ,
           for
           should
           you
           lift
           the
           Tube
           out
           in
           the
           Posture
           it
           stands
           in
           ,
           when
           going
           ,
           the
           Mercury
           ,
           by
           the
           Force
           of
           the
           Air
           's
           Pressing
           in
           at
           the
           open
           End
           ,
           would
           fly
           up
           to
           the
           top
           with
           such
           Violence
           as
           to
           endanger
           the
           breaking
           off
           of
           the
           top
           of
           the
           Glass
           .
        
         
           Note
           ,
           That
           if
           the
           Glass
           Tube
           be
           not
           well
           purged
           of
           Air
           ,
           the
           Quick-silver
           will
           ,
           by
           long
           standing
           ,
           be
           apt
           to
           move
           contrary
           to
           the
           true
           Nature
           of
           a
           Baroscope
           ,
           by
           reason
           that
           the
           Air
           which
           has
           been
           left
           in
           the
           Tube
           ,
           has
           by
           degrees
           got
           up
           into
           the
           Head
           or
           empty
           Space
           of
           it
           ,
           where
           being
           expanded
           by
           any
           accidental
           Heat
           of
           Air
           ,
           it
           occasions
           the
           Mercury
           to
           sink
           ,
           though
           the
           Weight
           and
           Pressure
           of
           the
           Air
           be
           no
           ways
           altered
           ;
           this
           is
           observed
           by
           Dr.
           
             Beale
             ,
             Phyl.
             Trans
          
           .
           numb
           .
           9.
           p.
           157.
           
           That
           a
           Baroscope
           ascended
           higher
           in
           the
           cold
           Mornings
           and
           Evenings
           than
           at
           Mid-day
           ;
           which
           doubtless
           proceeded
           from
           the
           aforesaid
           Cause
           ;
           for
           if
           you
           leave
           ,
           for
           tryal-sake
           ,
           a
           little
           Bubble
           of
           Air
           in
           the
           
           Head
           of
           the
           Glass
           when
           you
           set
           it
           up
           ,
           you
           will
           find
           the
           same
           Defect
           ,
           as
           Dr.
           Beale
           has
           observ'd
           .
        
         
           Wherefore
           't
           is
           necessary
           if
           you
           are
           doubtful
           of
           the
           like
           ,
           to
           Rectifie
           your
           Weather-Glass
           ,
           when
           it
           has
           been
           set
           up
           about
           a
           Twelve
           Month
           ;
           which
           is
           done
           by
           taking
           of
           the
           Tube
           down
           ,
           and
           repurging
           of
           it
           of
           Air
           ,
           as
           you
           were
           taught
           in
           first
           setting
           of
           it
           up
           :
           but
           that
           you
           may
           not
           be
           put
           to
           more
           trouble
           than
           needs
           ,
           you
           ought
           to
           be
           first
           certain
           that
           your
           Weather-Glass
           does
           want
           Rectifying
           ,
           which
           you
           may
           know
           thus
           ;
           Let
           the
           Tube
           as
           it
           stands
           in
           the
           Cestern
           be
           stoop'd
           down
           so
           low
           ,
           till
           the
           Mercury
           rise
           quite
           up
           to
           the
           Head
           ,
           and
           if
           you
           perceive
           a
           Bubble
           of
           Wind
           at
           the
           top
           above
           the
           Quicksilver
           ,
           that
           is
           the
           certain
           sign
           of
           its
           wanting
           to
           be
           new
           Rectified
           ;
           clap
           then
           your
           Finger
           under
           the
           open
           end
           in
           the
           Cestern
           ,
           and
           take
           it
           out
           and
           purge
           out
           the
           Air
           ,
           as
           before
           was
           directed
           ,
           at
           its
           first
           setting
           up
           .
        
         
           
           
             Of
             the
             Uses
             of
             the
             Baroscope
             ,
             or
             Quick-silver
             Weather-Glass
             .
          
           
             AND
             here
             it
             may
             not
             be
             amiss
             in
             the
             first
             place
             ,
             to
             shew
             you
             my
             Opinion
             concerning
             the
             Reasons
             of
             that
             different
             weight
             of
             Air
             which
             is
             now
             generally
             believ'd
             ,
             (
             and
             that
             with
             good
             Reason
             too
             )
             to
             be
             the
             cause
             of
             the
             Quicksilvers
             rising
             against
             fair
             ,
             and
             falling
             against
             foul
             Weather
             :
             Now
             the
             Reasons
             or
             Causes
             of
             this
             ,
             I
             take
             to
             be
             principally
             two
             ;
             the
             one
             is
             the
             Dilating
             and
             Contracting
             of
             the
             Air
             ;
             and
             the
             other
             is
             the
             Airs
             being
             empty
             of
             light
             Vapours
             ,
             and
             sometimes
             filled
             with
             them
             .
          
           
             That
             the
             Air
             is
             capable
             of
             Contraction
             and
             Expansion
             ,
             is
             plainly
             apparent
             by
             its
             dilating
             with
             Heat
             ,
             and
             contracting
             by
             Cold
             in
             the
             Bolt-head
             of
             a
             Thermoscope
             ,
             or
             Water
             Weather-Glass
             .
          
           
             Now
             if
             the
             Air
             be
             Contracted
             into
             a
             less
             room
             ,
             by
             what
             cause
             it
             will
             ,
             the
             Adjacent
             Air
             flows
             in
             to
             make
             good
             the
             Level
             of
             the
             Atmosphere
             ,
             and
             so
             by
             
             the
             Addition
             of
             more
             Air
             ,
             the
             Cylender
             which
             bouys
             up
             the
             Mercury
             in
             the
             Weather-Glass
             becomes
             heavier
             ,
             and
             by
             consequence
             makes
             the
             Quicksilver
             rise
             ;
             and
             though
             in
             Summer-time
             it
             may
             be
             thought
             that
             the
             Heat
             we
             feel
             should
             rather
             Expand
             than
             Contract
             ,
             yet
             in
             this
             we
             may
             be
             deceived
             ;
             for
             though
             the
             Air
             be
             Hot
             just
             at
             the
             Earth
             by
             the
             Sun's
             Reflection
             ,
             yet
             the
             upper
             Regions
             are
             still
             as
             Cold
             as
             ever
             ,
             witness
             the
             Snow
             which
             continues
             all
             the
             Year
             round
             on
             the
             Tops
             of
             some
             very
             high
             Mountains
             ,
             and
             so
             the
             Air
             may
             very
             well
             be
             accidentally
             contracted
             in
             the
             hottest
             time
             of
             Summer
             ,
             as
             well
             as
             in
             the
             coldest
             Winter
             ,
             and
             be
             one
             occasion
             of
             the
             Airs
             being
             then
             as
             heavy
             in
             dry
             Weather
             ,
             as
             in
             the
             fairest
             time
             of
             Winter
             .
          
           
             And
             as
             the
             Air
             is
             made
             heavier
             by
             Contraction
             ,
             so
             't
             is
             made
             lighter
             by
             Expansion
             ;
             for
             when
             its
             Body
             is
             rarified
             from
             what
             Cause
             soever
             ,
             the
             Swelling
             thereof
             causes
             the
             highest
             part
             to
             flow
             off
             ;
             or
             ,
             as
             I
             may
             say
             ,
             run
             down
             on
             those
             Parts
             of
             the
             Atmosphere
             that
             are
             below
             it
             ,
             by
             which
             means
             the
             Cylender
             ,
             or
             Pillar
             of
             it
             that
             presses
             on
             any
             Place
             becomes
             
             lighter
             ,
             and
             so
             the
             Mercury
             in
             the
             Baroscope
             is
             suffered
             to
             sink
             down
             or
             descend
             .
          
           
             And
             that
             the
             Airs
             being
             sometimes
             full
             of
             watry
             Vapours
             ,
             and
             sometimes
             empty
             ,
             is
             another
             and
             the
             chief
             Reason
             too
             of
             the
             Quicksilvers
             rising
             and
             falling
             ,
             is
             manifest
             from
             this
             Principle
             in
             Philosophy
             ,
             That
             what-ever
             Rises
             up
             and
             Swims
             in
             any
             Medium
             ,
             must
             Bulk
             for
             Bulk
             be
             lighter
             than
             the
             Medium
             by
             which
             it
             is
             sustained
             :
             Hence
             it
             follows
             ,
             that
             all
             kinds
             of
             watry
             Vapours
             must
             be
             lighter
             than
             the
             Air
             ,
             else
             they
             could
             never
             rise
             up
             therein
             ,
             nor
             be
             suspended
             there
             ,
             till
             by
             another
             Principle
             in
             Nature
             they
             are
             made
             to
             descend
             in
             Rain
             or
             Snow
             .
             Now
             if
             Water
             thus
             Rarified
             be
             specifically
             lighter
             than
             Air
             ,
             then
             't
             is
             plain
             ,
             that
             when
             the
             Air
             is
             filled
             therewith
             ,
             it
             must
             become
             less
             weighty
             than
             it
             was
             before
             :
             As
             a
             Glass
             filled
             with
             half
             Water
             and
             half
             rectified
             Spirit
             of
             Wine
             ,
             a
             much
             lighter
             substance
             ,
             shall
             not
             weigh
             so
             much
             as
             when
             fill'd
             with
             all
             Water
             ;
             so
             the
             Air
             is
             always
             lightest
             in
             wet
             Weather
             ,
             because
             the
             Spaces
             above
             us
             are
             then
             full
             of
             Vapours
             ,
             much
             lighter
             
             than
             the
             Air
             is
             ,
             and
             by
             consequence
             the
             Body
             of
             Air
             and
             watry
             Particles
             mixt
             together
             ,
             must
             weigh
             less
             than
             if
             the
             whole
             were
             only
             an
             unmixt
             and
             pure
             Air.
             
          
           
             On
             the
             contrary
             ,
             when
             the
             Air
             is
             dry
             and
             free
             from
             being
             thus
             fill'd
             with
             watry
             Vapours
             ,
             it
             must
             then
             be
             most
             heavy
             at
             such
             times
             :
             Indeed
             we
             may
             perceive
             many
             large
             white
             and
             curled
             Clouds
             sailing
             aloft
             over
             us
             ,
             but
             these
             are
             only
             a
             Collection
             of
             some
             few
             Vapours
             in
             the
             very
             upper
             Region
             of
             the
             Air
             ,
             the
             Spaces
             below
             being
             in
             the
             mean
             time
             very
             little
             ,
             or
             not
             at
             all
             filled
             therewith
             ;
             whereas
             in
             very
             wet
             Weather
             ,
             when
             the
             Glass
             is
             low
             ,
             and
             the
             Air
             very
             light
             ,
             we
             see
             not
             only
             the
             upper
             Region
             full
             of
             compacted
             Vapours
             ,
             but
             find
             also
             the
             whole
             Atmosphere
             even
             down
             to
             the
             Surface
             of
             the
             Earth
             filled
             therewith
             ;
             as
             is
             manifest
             by
             the
             Sweating
             of
             Stones
             ,
             and
             other
             tokens
             of
             the
             Airs
             extream
             Humidity
             ,
             and
             by
             consequence
             the
             fuller
             of
             light
             matter
             ,
             the
             Spaces
             above
             us
             are
             ,
             the
             less
             will
             the
             Weight
             be
             that
             presses
             downward
             ;
             and
             for
             that
             
             Reason
             the
             Glass
             in
             the
             wettest
             Weather
             always
             sinks
             lowest
             .
          
           
             This
             being
             premised
             ,
             I
             come
             to
             the
             more
             particular
             Uses
             of
             the
             Glass
             ;
             and
             first
             ,
             you
             may
             perceive
             by
             what
             has
             been
             said
             ,
             That
             the
             Glass
             gives
             a
             very
             good
             account
             of
             the
             Temper
             of
             the
             Air
             as
             to
             its
             Moisture
             or
             Driness
             ,
             the
             Moisture
             thereof
             ,
             or
             its
             Fulness
             of
             watry
             Vapours
             ,
             being
             always
             proportionable
             to
             the
             lowness
             of
             the
             Quicksilver
             ,
             and
             every
             Degree
             of
             Sinking
             is
             an
             argument
             of
             the
             Airs
             being
             filled
             more
             and
             more
             with
             Moisture
             ,
             and
             the
             lower
             its
             Station
             ,
             the
             more
             full
             of
             Moisture
             the
             Air
             still
             is
             ;
             and
             you
             shall
             always
             observe
             ,
             That
             the
             lower
             the
             Quicksilver
             descends
             ,
             the
             more
             listless
             and
             out
             of
             order
             Men's
             Bodies
             are
             ,
             because
             the
             Air
             is
             then
             full
             of
             that
             which
             is
             disagreeable
             to
             the
             Nature
             of
             Man
             ,
             who
             was
             not
             made
             to
             live
             in
             a
             Watry
             Element
             :
             and
             therefore
             the
             more
             Watry
             the
             Medium
             is
             in
             which
             he
             lives
             ,
             the
             more
             is
             his
             Nature
             disturbed
             at
             it
             .
          
           
           
             On
             the
             contrary
             ,
             The
             higher
             the
             Quicksilver
             is
             ,
             the
             drier
             still
             is
             the
             Air
             ;
             and
             by
             consequence
             Men's
             Bodies
             are
             then
             found
             to
             be
             more
             Brisk
             and
             Lively
             ,
             because
             the
             Medium
             in
             which
             they
             live
             and
             move
             ,
             is
             free
             from
             what
             their
             Nature
             abhors
             ;
             so
             that
             by
             the
             Weather-Glass
             may
             be
             known
             in
             great
             part
             ,
             whether
             the
             Disorder
             and
             Melancholy
             ,
             or
             the
             Periodical
             Pains
             and
             Aches
             to
             which
             we
             are
             sometimes
             unavoidably
             subject
             ,
             is
             really
             occasioned
             by
             a
             new
             bodily
             Distemper
             or
             not
             ;
             for
             this
             happening
             when
             the
             Quicksilver
             is
             low
             ,
             may
             be
             judg'd
             to
             be
             occasioned
             rather
             by
             the
             Air
             ,
             and
             by
             consequence
             will
             go
             off
             naturally
             of
             it self
             when
             the
             Quicksilver
             rises
             ;
             a
             too
             moist
             Air
             has
             stranger
             Effects
             on
             Men's
             Bodies
             ,
             than
             is
             generally
             taken
             notice
             of
             by
             them
             that
             understand
             not
             the
             Reason
             from
             whence
             it
             proceeds
             .
          
           
             In
             the
             next
             place
             observe
             ,
             That
             as
             the
             Baroscope
             Predicts
             only
             fair
             and
             foul
             Weather
             ,
             so
             that
             you
             may
             be
             the
             better
             directed
             which
             of
             these
             to
             expect
             ;
             you
             must
             still
             note
             the
             rising
             and
             falling
             of
             the
             Mercury
             ;
             for
             its
             rising
             in
             
             any
             part
             of
             the
             Glass
             ,
             betokens
             a
             tendency
             to
             fair
             ,
             as
             its
             falling
             down
             foreshews
             an
             inclination
             to
             Rain
             and
             Wet
             :
             As
             for
             the
             Words
             engraven
             on
             the
             upper
             part
             of
             the
             
               Register
               Plats
            
             ,
             they
             are
             then
             only
             to
             be
             noted
             when
             the
             Mercury
             removes
             from
             Changeable
             upwards
             ,
             and
             those
             on
             the
             lower
             part
             are
             to
             be
             noted
             only
             when
             the
             Quicksilver
             falls
             from
             Changeable
             downward
             .
          
           
             In
             other
             Cases
             the
             Words
             are
             of
             no
             Use
             ;
             for
             if
             it
             is
             Rising
             in
             any
             part
             ,
             foreshews
             a
             Tendency
             to
             be
             Fair
             ,
             and
             its
             Falling
             in
             any
             part
             ,
             a
             Tendency
             to
             foul
             Weather
             ;
             then
             it
             follows
             ,
             that
             if
             it
             fall
             from
             settled
             Fair
             to
             Fair
             ,
             it
             may
             yet
             Rain
             a
             little
             ,
             though
             the
             Quicksilver
             still
             stands
             as
             high
             as
             Fair
             ;
             the
             like
             may
             be
             said
             ,
             if
             it
             rise
             from
             the
             Word
             ,
             much
             Rain
             to
             Rain
             ;
             for
             though
             its
             Rising
             betoken
             a
             Tendency
             to
             Fair
             ,
             yet
             since
             't
             is
             still
             so
             low
             as
             the
             Word
             Rain
             ,
             there
             may
             be
             yet
             be
             some
             Wet
             Weather
             ,
             though
             not
             so
             much
             as
             there
             was
             before
             the
             Quick-silver
             began
             to
             rise
             .
          
           
             But
             if
             the
             Mercury
             mount
             upwards
             from
             Changeable
             ,
             then
             will
             the
             Weather
             for
             the
             most
             part
             be
             such
             as
             the
             
             Words
             in
             the
             upper
             part
             of
             the
             Register
             Plates
             Import
             ;
             and
             if
             from
             Changeable
             it
             falls
             down
             ,
             the
             Weather
             likewise
             will
             be
             much
             the
             same
             ,
             as
             the
             Words
             found
             in
             that
             Part
             do
             express
             ;
             but
             in
             the
             Mercuries
             rising
             up
             to
             Changeable
             when
             't
             is
             below
             it
             ,
             or
             falling
             when
             't
             is
             above
             it
             ,
             the
             Words
             as
             I
             said
             before
             ,
             signifie
             nothing
             .
          
           
             If
             the
             Mercury
             rises
             very
             high
             ,
             the
             Weather
             will
             continue
             Fair
             ,
             so
             long
             as
             it
             stands
             at
             that
             pitch
             ,
             and
             you
             will
             not
             find
             the
             Weather
             change
             much
             ,
             till
             the
             Mercury
             falls
             down
             a
             good
             Space
             lower
             :
             So
             likewise
             when
             't
             is
             fallen
             down
             very
             low
             ,
             you
             must
             expect
             Wet
             Weather
             during
             all
             the
             time
             of
             its
             so
             continuing
             ;
             in
             both
             these
             Particulars
             you
             will
             be
             certain
             ,
             provided
             the
             Wind
             and
             the
             Moon
             Concur
             .
          
           
             For
             both
             the
             Wind
             and
             the
             Changes
             of
             the
             Moon
             are
             to
             be
             well
             observed
             in
             order
             to
             make
             the
             truer
             Prediction
             :
             And
             first
             ,
             for
             the
             Wind
             ;
             this
             is
             found
             to
             be
             of
             very
             great
             Moment
             ;
             for
             if
             the
             Glass
             fall
             ,
             and
             the
             Wind
             sit
             in
             those
             Quarters
             ,
             from
             whence
             much
             Rain
             is
             observed
             usually
             to
             come
             ;
             as
             with
             us
             
             about
             London
             are
             the
             South
             and
             Southwest
             ,
             then
             't
             is
             not
             to
             be
             doubted
             but
             Wet
             will
             follow
             .
             On
             the
             contrary
             ,
             if
             the
             Glass
             rise
             when
             the
             Wind
             blows
             from
             a
             dry
             Quarter
             of
             the
             Heavens
             ;
             as
             with
             us
             are
             the
             North
             and
             East
             ,
             then
             't
             is
             a
             hundred
             to
             one
             but
             the
             Weather
             will
             be
             Fair
             ;
             but
             if
             the
             Glass
             rises
             ,
             and
             the
             Wind
             be
             South
             ,
             the
             Case
             is
             doubtful
             :
             So
             also
             if
             it
             falls
             ,
             and
             the
             Wind
             be
             North
             ,
             for
             then
             it
             often
             happens
             that
             the
             Weather
             does
             not
             prove
             always
             such
             as
             the
             Rising
             and
             Falling
             of
             the
             Glass
             Predicts
             .
          
           
             As
             to
             the
             Moon
             ,
             't
             is
             well
             observed
             ,
             That
             the
             Weather
             is
             generally
             inclinable
             to
             Moisture
             ,
             about
             three
             Days
             before
             ,
             and
             three
             Days
             after
             ,
             both
             the
             New
             and
             
               Full
               Moon
            
             ;
             if
             therefore
             the
             Glass
             Falls
             ,
             the
             Wind
             be
             South
             ,
             and
             the
             Moon
             near
             the
             New
             or
             Full
             ,
             the
             certainty
             of
             Rain
             is
             still
             much
             the
             greater
             .
          
           
             If
             the
             Mercury
             be
             high
             in
             the
             Summer-time
             when
             the
             Weather
             is
             hot
             ,
             and
             does
             of
             a
             suddain
             fall
             down
             a
             pretty
             considerable
             Distance
             ,
             then
             certainly
             expect
             great
             and
             sudden
             Storms
             of
             Rain
             and
             Thunder
             to
             follow
             soon
             after
             .
          
           
             VVhen
             the
             Glass
             is
             Risen
             very
             high
             in
             Winter
             ,
             and
             the
             Wind
             sits
             then
             
             North
             and
             East
             ,
             it
             certainly
             presages
             Frost
             to
             ensue
             ,
             and
             the
             same
             will
             continue
             as
             long
             as
             the
             Mercury
             stands
             thus
             High
             ;
             but
             when
             you
             see
             it
             begin
             to
             sink
             somewhat
             considerably
             ,
             then
             be
             assured
             a
             Thaw
             will
             quickly
             follow
             .
          
           
             If
             in
             a
             Frost
             the
             Air
             becomes
             Overcast
             ,
             and
             the
             Quicksilver
             Rises
             of
             a
             suddain
             yet
             higher
             ,
             when
             it
             had
             stood
             high
             for
             a
             time
             before
             ,
             then
             look
             for
             Snow
             ,
             for
             the
             Cold
             above
             ,
             which
             is
             the
             Cause
             of
             Snow
             ,
             causes
             also
             the
             Air
             to
             become
             more
             heavy
             by
             Condensatition
             .
          
           
             If
             the
             Glass
             Rise
             and
             Fall
             but
             a
             little
             ,
             or
             it
             be
             unsettled
             in
             its
             Motion
             ,
             it
             then
             argues
             an
             unconstant
             Season
             ,
             and
             the
             Weather
             will
             not
             then
             long
             continue
             in
             one
             state
             ;
             the
             like
             happens
             when
             it
             is
             about
             the
             Word
             Changeable
             ,
             or
             Uncertain
             ,
             for
             then
             no
             true
             Guess
             can
             be
             made
             what
             the
             VVeather
             will
             be
             .
          
           
             The
             Mercury
             is
             always
             observed
             to
             be
             lowest
             in
             extream
             high
             and
             strong
             Winds
             ,
             that
             happen
             when
             the
             Air
             is
             full
             of
             Moisture
             ;
             but
             the
             Glass
             does
             no
             way
             predict
             Winds
             before-hand
             ,
             for
             the
             extreme
             
             lowness
             of
             the
             Quick-silver
             happens
             only
             at
             the
             very
             Time
             the
             Wind
             Blows
             ,
             and
             as
             soon
             as
             the
             Wind
             Ceases
             the
             Mercury
             is
             then
             found
             to
             rise
             apace
             ,
             but
             such
             a
             Rise
             that
             immediately
             follows
             Storms
             ,
             are
             no
             signs
             of
             fair
             Weather
             ,
             except
             it
             rises
             much
             higher
             than
             it
             was
             at
             the
             Time
             of
             the
             Wind
             's
             beginning
             to
             blow
             .
          
           
             Note
             ,
             That
             when
             Wet
             is
             predicted
             by
             the
             Glass
             ,
             or
             by
             any
             other
             Sign
             or
             Token
             ,
             it
             generally
             begins
             to
             rain
             either
             when
             the
             Moon
             is
             due
             South
             ,
             or
             else
             when
             the
             Sun
             comes
             to
             be
             upon
             the
             same
             Quarter
             from
             whence
             the
             Wind
             blows
             ;
             and
             if
             it
             rains
             not
             at
             the
             Time
             of
             the
             Moon
             's
             Southing
             or
             Northing
             ,
             nor
             when
             the
             Sun
             and
             the
             Wind
             comes
             together
             ,
             then
             't
             will
             hardly
             rain
             till
             the
             same
             Times
             do
             again
             return
             ;
             which
             is
             a
             good
             Note
             in
             time
             of
             Harvest
             ,
             and
             very
             seldom
             fails
             ,
             though
             it
             sometimes
             may
             .
          
           
             Note
             also
             ,
             that
             most
             great
             Changes
             of
             the
             Weather
             happen
             with
             us
             ,
             either
             at
             the
             New
             full
             Moon
             ;
             and
             if
             the
             Weather
             change
             not
             then
             ,
             't
             will
             hold
             on
             as
             it
             is
             till
             the
             next
             New
             or
             Full
             Moon
             comes
             :
             Frost
             generally
             breaks
             at
             the
             Changes
             ,
             
             when
             it
             does
             break
             ,
             and
             't
             is
             commonly
             at
             the
             Change
             or
             Full
             that
             Rain
             comes
             ,
             after
             a
             dry
             Season
             has
             long
             continued
             .
          
        
         
           
             An
             Addition
             of
             some
             
               Natural
               Predictions
            
             of
             Fair
             and
             
               Foul
               Weather
            
             :
             And
             first
             of
             
               Fair
               Weather
            
             .
          
           
             THe
             much
             hooping
             of
             Owls
             ,
             after
             Sun-set
             ,
             in
             the
             
             Summer-time
             ,
             and
             in
             the
             Night
             also
             ,
             foreshews
             a
             fair
             Day
             to
             follow
             .
          
           
             Swarms
             of
             little
             Gnats
             and
             Flies
             ,
             sporting
             themselves
             together
             ,
             in
             the
             Evening
             ,
             is
             a
             certain
             token
             that
             the
             Day
             following
             will
             be
             fair
             .
          
           
             If
             the
             Sun
             set
             red
             in
             the
             Evening
             ,
             and
             the
             Place
             be
             free
             from
             Clouds
             ,
             and
             the
             next
             Morning
             rises
             clear
             and
             bright
             ;
             these
             are
             good
             tokens
             that
             the
             Day
             will
             be
             fair
             .
          
           
             The
             Soaring
             of
             Kites
             aloft
             in
             the
             Air
             ,
             is
             a
             Sign
             of
             dry
             and
             hot
             Weather
             .
          
           
           
             When
             the
             Bat
             Mice
             are
             seen
             to
             fly
             to
             and
             fro
             ,
             in
             the
             Evening
             ,
             it
             shews
             that
             the
             next
             will
             be
             a
             fair
             Day
             .
          
           
             If
             ,
             in
             the
             Morning
             ,
             Mists
             descend
             from
             the
             Hills
             ,
             and
             settle
             in
             the
             Vallies
             ,
             't
             is
             a
             Sign
             that
             the
             Day
             will
             be
             fair
             .
          
           
             If
             it
             rain
             in
             the
             Summer
             ,
             and
             Horses
             and
             Kine
             do
             thereupon
             leave
             off
             Feeding
             ,
             't
             is
             a
             certain
             Sign
             the
             Rain
             will
             not
             continue
             long
             .
          
           
             Crows
             ,
             if
             they
             caw
             or
             cry
             early
             in
             the
             Morning
             ,
             with
             a
             loud
             and
             clear
             Voice
             ,
             it
             shews
             that
             the
             Day
             will
             be
             fair
             .
          
           
             
               
                 Signs
                 of
              
               Rain
               and
               Wet
               Weather
               .
            
             
               IF
               ,
               in
               the
               Evening
               ,
               the
               Sun
               set
               behind
               a
               dark
               black
               Cloud
               ,
               and
               her
               Body
               appear
               also
               greater
               at
               that
               Time
               than
               usual
               ,
               it
               certainly
               betokens
               Wet
               the
               next
               Day
               .
            
             
               If
               Water-fowl
               wash
               themselves
               much
               and
               dive
               more
               than
               usual
               under
               Water
               ,
               and
               also
               flutter
               and
               clap
               their
               Wings
               ,
               
               and
               oil
               their
               Feathers
               more
               than
               usual
               ,
               't
               is
               a
               Sign
               of
               Rain
               .
            
             
               If
               Toads
               are
               ,
               in
               the
               Evening
               ,
               found
               leaping
               in
               the
               Paths
               or
               High
               Ways
               ,
               or
               if
               the
               great
               black
               Houseless
               Snails
               are
               found
               creeping
               about
               more
               than
               usual
               ,
               it
               foreshews
               Rain
               .
            
             
               An
               unusual
               Circle
               of
               Light
               about
               the
               Moon
               or
               Stars
               ,
               when
               no
               Mist
               or
               Fog
               appears
               below
               ,
               is
               a
               Sign
               of
               Rain
               soon
               to
               follow
               .
            
             
               If
               the
               Sun
               ,
               at
               her
               first
               rising
               ,
               or
               some
               Time
               after
               ,
               shine
               waterish
               ,
               that
               is
               ,
               paler
               than
               ordinary
               ,
               't
               is
               a
               Sign
               of
               a
               wet
               Day
               ,
               especially
               if
               the
               Air
               be
               soon
               after
               obscured
               with
               thick
               Clouds
               .
            
             
               If
               ,
               in
               the
               Summer
               ,
               in
               a
               fair
               clear
               Day
               ,
               you
               perceive
               the
               Clouds
               to
               gather
               of
               a
               suddain
               on
               all
               Sides
               ,
               and
               appear
               black
               and
               curled
               ,
               then
               prepare
               your self
               for
               Storms
               of
               Rain
               and
               Thunder
               soon
               after
               .
            
             
               Hoggs
               crying
               in
               an
               unusual
               manner
               ,
               and
               running
               unquietly
               up
               and
               down
               ,
               with
               Litter
               in
               their
               Mouths
               ,
               foreshews
               Rain
               and
               Storms
               at
               Hand
               .
            
             
               If
               Crows
               cry
               much
               in
               the
               Evening
               ,
               't
               is
               a
               Sign
               of
               Rain
               the
               next
               Day
               .
            
             
             
               Any
               of
               these
               ,
               or
               the
               like
               Signs
               ,
               happening
               in
               the
               Summer
               time
               ,
               will
               ,
               if
               the
               Baroscope
               concur
               ,
               help
               you
               to
               make
               the
               more
               certain
               Guess
               at
               what
               Weather
               will
               after
               ensue
               ,
               especially
               if
               the
               Glass
               be
               at
               Changeable
               and
               Uncertain
               ,
               for
               then
               ,
               by
               these
               you
               may
               the
               better
               guess
               at
               what
               Weather
               will
               follow
               .
               Some
               particular
               Places
               have
               also
               Signs
               of
               Rain
               and
               fair
               Weather
               ,
               which
               others
               have
               not
               ,
               which
               observed
               ,
               together
               with
               the
               Glass
               ,
               may
               make
               your
               Guess
               more
               certain
               than
               they
               can
               otherwise
               be
               ;
               the
               Nature
               of
               Countries
               also
               differ
               ,
               for
               whereas
               in
               England
               ,
               especially
               near
               London
               and
               the
               Southern
               Parts
               ,
               a
               South
               Wind
               always
               brings
               most
               Rain
               ,
               and
               a
               North
               or
               East
               Wind
               dry
               Weather
               ;
               on
               the
               contrary
               ,
               at
               Edenburgh
               it
               Scotland
               a
               South
               Wind
               brings
               the
               fairest
               Weather
               ,
               and
               a
               North
               or
               North
               East
               the
               greatest
               Wet
               ;
               these
               things
               considered
               ,
               every
               Man
               that
               lives
               in
               Countries
               which
               differ
               in
               Temper
               from
               that
               for
               which
               these
               Rules
               serve
               ,
               ought
               to
               frame
               Rules
               to
               himself
               ,
               by
               observing
               the
               Changes
               that
               follow
               the
               Glass's
               Rising
               and
               Falling
               ,
               the
               Change
               of
               the
               Wind
               ,
               and
               the
               Southing
               of
               the
               Moon
               .
            
             
             
             
             
             
             
               Note
               ,
               If
               the
               latter
               End
               of
               February
               and
               the
               Beginning
               of
               March
               be
               constantly
               Dry
               ,
               it
               betokens
               a
               very
               Dry
               Summer
               .
               Also
               a
               hard
               Frostly
               and
               Snowy
               Winter
               makes
               the
               Year
               following
               to
               be
               very
               Plentiful
               and
               Healthy
               ,
               but
               a
               Warm
               and
               Moist
               Winter
               makes
               the
               Summer
               after
               to
               be
               very
               sickly
               .
            
          
        
         
           
             Some
             Uses
             of
             the
             Spirit
             Weather-Glass
             .
          
           
             THE
             suddain
             Rising
             of
             the
             Spirit
             in
             the
             Day
             ,
             in
             Summer
             ,
             foreshews
             an
             immediate
             Approach
             of
             Thunder
             and
             Storms
             of
             Rain
             ,
             and
             in
             Winter
             Snow
             .
          
           
             If
             it
             rises
             much
             in
             the
             Day
             and
             falls
             but
             little
             in
             the
             Night
             ,
             then
             expect
             ,
             the
             Day
             following
             ,
             excessive
             Heat
             ,
             if
             not
             Thunder
             and
             Storms
             .
          
           
           
             If
             it
             rises
             never
             so
             little
             in
             the
             Night-time
             ,
             expect
             next
             Day
             either
             Rain
             or
             Snow
             ,
             as
             the
             Season
             is
             .
          
           
             If
             it
             rises
             no
             more
             in
             the
             Day
             than
             it
             falls
             in
             the
             Night
             ,
             't
             is
             a
             Token
             that
             the
             Air
             is
             Temperate
             ,
             as
             to
             the
             Heat
             and
             Cold.
             
          
           
             If
             it
             falls
             in
             the
             Day-time
             ,
             and
             the
             Weather
             be
             fair
             ,
             expect
             a
             Frost
             the
             next
             Night
             .
             The
             like
             happens
             also
             generally
             when
             the
             Liquor
             is
             very
             low
             .
          
           
             The
             more
             it
             rises
             or
             falls
             at
             any
             Time
             the
             more
             remarkable
             will
             that
             Change
             of
             Weather
             be
             which
             follows
             .
          
           
             All
             the
             other
             Uses
             of
             it
             are
             only
             to
             shew
             the
             present
             Temper
             of
             the
             Air
             ,
             as
             to
             Heat
             and
             Cold
             ,
             and
             farther
             than
             this
             my
             Experience
             has
             not
             as
             yet
             led
             me
             ,
             neither
             by
             Enquiry
             do
             I
             find
             any
             other
             useful
             Observations
             made
             on
             them
             .
          
           
             I
             shall
             only
             add
             ,
             That
             these
             Glasses
             might
             be
             made
             as
             strong
             as
             the
             Tube
             of
             a
             Quick-silver
             Weather
             glass
             ,
             provided
             the
             Ball
             be
             proportionable
             to
             the
             Bore
             only
             .
             It
             may
             be
             ,
             if
             the
             Glass
             were
             thicker
             ,
             they
             would
             not
             move
             so
             nicely
             ;
             but
             this
             would
             not
             signify
             much
             ,
             because
             little
             Judgment
             can
             be
             made
             from
             small
             and
             little
             Alterations
             .
          
           
           
             JUst
             when
             the
             last
             Sheet
             was
             ready
             to
             be
             printed
             off
             ,
             that
             which
             follows
             was
             communicated
             to
             me
             by
             Mr
             Watson
             ,
             the
             Person
             before-mentioned
             in
             this
             Work
             ,
             which
             in
             respect
             of
             its
             Nature
             ,
             being
             not
             only
             plain
             and
             useful
             ,
             but
             also
             free
             from
             all
             Objections
             that
             Tables
             may
             be
             liable
             to
             ,
             I
             have
             thought
             fit
             to
             add
             it
             hereunto
             ,
             upon
             his
             Recommendation
             ,
             and
             in
             the
             Words
             penn'd
             by
             himself
             .
          
           
             
               
                 
                   SIR
                
              
               
                 I
                 Rather
                 communicate
                 this
                 to
                 you
                 ,
                 because
                 many
                 Gentlemen
                 have
                 the
                 Convenience
                 of
                 Places
                 fit
                 for
                 this
                 way
                 of
                 Observation
                 ,
                 which
                 I
                 take
                 to
                 be
                 the
                 most
                 exact
                 Way
                 yet
                 found
                 to
                 adjust
                 a
                 Pendulum
                 Clock
                 well
                 .
                 If
                 you
                 think
                 it
                 may
                 be
                 serviceable
                 to
                 those
                 that
                 are
                 the
                 most
                 exact
                 and
                 curious
                 in
                 Time-keeping
                 ,
                 you
                 may
                 do
                 well
                 to
                 insert
                 it
                 in
                 that
                 laborious
                 and
                 curious
                 Tract
                 of
                 the
                 
                   Equation
                   of
                   Natural
                   Days
                
                 ,
                 that
                 you
                 are
                 now
                 publishing
                 .
                 I
                 am
                 ,
              
               
                 
                   Your
                   real
                   Friend
                   and
                   humble
                   Servant
                   ,
                   S.
                   W.
                   
                
              
            
          
           
             
             
               The
               Way
               of
               finding
               how
               much
               a
               
                 Pendulum
                 Clock
              
               has
               gained
               or
               lost
               in
               a
               Day
               ,
               Week
               or
               a
               Month
               ,
               to
               the
               nicity
               of
               Two
               or
               Three
               Seconds
               ,
               &c.
               
            
             
               
                 
                   
                     N.
                     
                  
                   
                     h.
                     
                  
                   
                     ′
                  
                   
                     ″
                  
                
                 
                   
                     1
                  
                   
                     0
                  
                   
                     3
                  
                   
                     56
                  
                
                 
                   
                     2
                  
                   
                     0
                  
                   
                     7
                  
                   
                     52
                  
                
                 
                   
                     3
                  
                   
                     0
                  
                   
                     11
                  
                   
                     48
                  
                
                 
                   
                     4
                  
                   
                     0
                  
                   
                     15
                  
                   
                     44
                  
                
                 
                   
                     5
                  
                   
                     0
                  
                   
                     19
                  
                   
                     39
                  
                
                 
                   
                     6
                  
                   
                     0
                  
                   
                     23
                  
                   
                     35
                  
                
                 
                   
                     7
                  
                   
                     0
                  
                   
                     27
                  
                   
                     31
                  
                
                 
                   
                     8
                  
                   
                     0
                  
                   
                     31
                  
                   
                     27
                  
                
                 
                   
                     9
                  
                   
                     0
                  
                   
                     35
                  
                   
                     23
                  
                
                 
                   
                     10
                  
                   
                     0
                  
                   
                     39
                  
                   
                     19
                  
                
                 
                   
                     11
                  
                   
                     0
                  
                   
                     43
                  
                   
                     15
                  
                
                 
                   
                     12
                  
                   
                     0
                  
                   
                     47
                  
                   
                     11
                  
                
                 
                   
                     13
                  
                   
                     0
                  
                   
                     51
                  
                   
                     7
                  
                
                 
                   
                     14
                  
                   
                     0
                  
                   
                     55
                  
                   
                     2
                  
                
                 
                   
                     15
                  
                   
                     0
                  
                   
                     58
                  
                   
                     58
                  
                
                 
                   
                     16
                  
                   
                     1
                  
                   
                     2
                  
                   
                     54
                  
                
                 
                   
                     17
                  
                   
                     1
                  
                   
                     6
                  
                   
                     50
                  
                
                 
                   
                     18
                  
                   
                     1
                  
                   
                     10
                  
                   
                     46
                  
                
                 
                   
                     19
                  
                   
                     1
                  
                   
                     14
                  
                   
                     42
                  
                
                 
                   
                     20
                  
                   
                     1
                  
                   
                     18
                  
                   
                     38
                  
                
                 
                   
                     21
                  
                   
                     1
                  
                   
                     22
                  
                   
                     34
                  
                
                 
                   
                     22
                  
                   
                     1
                  
                   
                     26
                  
                   
                     30
                  
                
                 
                   
                     23
                  
                   
                     1
                  
                   
                     30
                  
                   
                     25
                  
                
                 
                   
                     24
                  
                   
                     1
                  
                   
                     34
                  
                   
                     21
                  
                
                 
                   
                     25
                  
                   
                     1
                  
                   
                     38
                  
                   
                     17
                  
                
                 
                   
                     26
                  
                   
                     1
                  
                   
                     42
                  
                   
                     13
                  
                
                 
                   
                     27
                  
                   
                     1
                  
                   
                     46
                  
                   
                     9
                  
                
                 
                   
                     28
                  
                   
                     1
                  
                   
                     50
                  
                   
                     5
                  
                
                 
                   
                     29
                  
                   
                     1
                  
                   
                     54
                  
                   
                     1
                  
                
                 
                   
                     30
                  
                   
                     1
                  
                   
                     57
                  
                   
                     57
                  
                
                 
                   
                     31
                  
                   
                     2
                  
                   
                     1
                  
                   
                     53
                  
                
              
            
             
               TAke
               a
               Piece
               of
               thin
               Brass
               ,
               and
               file
               therein
               a
               Slit
               or
               Notch
               ,
               about
               half
               a
               quarter
               of
               an
               Inch
               deep
               ,
               but
               somewhat
               wider
               at
               the
               Top
               than
               at
               the
               Bottom
               ,
               as
               thus
               〈◊〉
               ,
               knock
               the
               End
               of
               it
               into
               some
               Post
               in
               your
               Back-side
               ,
               or
               else
               in
               some
               Window
               ,
               that
               ye
               think
               convenient
               ;
               then
               look
               through
               the
               Notch
               at
               any
               Star
               of
               the
               first
               or
               second
               Magnitude
               ,
               and
               wait
               till
               the
               Star
               comes
               to
               the
               Edge
               of
               any
               Chimney
               ,
               or
               the
               Side
               of
               any
               House
               ,
               and
               you
               will
               see
               the
               Star
               vanish
               in
               a
               Moment
               ;
               then
               mark
               what
               your
               Clock
               is
               at
               
               when
               the
               Star
               vanishes
               :
               Then
               at
               any
               other
               Night
               afterwards
               (
               as
               the
               next
               Night
               ,
               or
               a
               Week
               or
               a
               Month
               afterwards
               )
               wait
               for
               the
               same
               Star
               again
               till
               it
               vanish
               behind
               the
               Chimney
               or
               House
               ,
               as
               before
               ,
               and
               then
               observe
               what
               your
               Clock
               is
               at
               ,
               then
               your
               Clock
               should
               shew
               the
               second
               Time
               of
               vanishing
               so
               much
               sooner
               than
               the
               first
               ,
               as
               this
               Table
               shews
               ;
               now
               the
               farther
               off
               the
               Chimney
               or
               Wall
               is
               the
               more
               exact
               will
               the
               Observation
               be
               .
               Let
               the
               Distance
               be
               Ten
               Yards
               at
               least
               ,
               let
               the
               Observation
               be
               made
               in
               any
               part
               of
               the
               
                 East
                 ,
                 South
              
               or
               West
               ,
               but
               little
               towards
               the
               
                 North
                 Pole
              
               ,
               because
               the
               
                 Polar
                 Stars
              
               are
               not
               so
               fit
               for
               this
               Purpose
               .
            
             
               EXAMPLE
               .
            
             
               Suppose
               a
               Star
               vanishes
               this
               Night
               at
               Nine
               Hours
               ,
               Three
               Minutes
               and
               Four
               Seconds
               ,
               by
               my
               Clock
               ,
               and
               Eight
               Nights
               after
               I
               observe
               it
               again
               ,
               and
               it
               then
               vanishes
               at
               Eight
               Hours
               ,
               Thirty
               four
               Minutes
               and
               Forty
               two
               Seconds
               ;
               by
               my
               Clock
               ,
               against
               Eight
               Nights
               ,
               in
               the
               Table
               ,
               I
               find
               Thirty
               one
               Minutes
               Twenty
               seven
               Seconds
               ;
               that
               is
               ,
               so
               much
               sooner
               should
               the
               Star
               vanish
               at
               the
               second
               Observation
               than
               it
               did
               at
               the
               first
               ;
               therefore
               substracting
               31′
               27″
               from
               the
               first
               Observation
               9h
               .
               3′
               4″
               .
               there
               's
               left
               8h
               .
               31′
               37″
               ,
               the
               true
               Time
               that
               the
               Clock
               should
               have
               been
               at
               in
               the
               second
               Observation
               ;
               therefore
               seeing
               the
               Clock
               was
               then
               at
               8h
               24′
               32″
               ,
               it
               has
               gained
               2′
               55.
               
            
          
        
         
           FINIS
           .
        
         
      
    
     
  

