﻿THE 
  CIRCUMSTANCES 
  OF 
  AN 
  ECLIPSE 
  OF 
  THE 
  SUN. 
  299 
  

  

  duced 
  to 
  seconds, 
  by 
  10, 
  and 
  divide 
  the 
  product 
  by 
  the 
  difference 
  of 
  

   the 
  parallaxes, 
  also 
  reduced 
  to 
  seconds, 
  extending 
  the 
  quotient 
  to 
  two 
  

   decimal 
  places, 
  and 
  denote 
  it 
  by 
  q. 
  Do 
  the 
  same 
  with 
  the 
  difference 
  

   of 
  the 
  horary 
  motions 
  in 
  right 
  ascension, 
  denoting 
  the 
  quotient 
  by 
  P'; 
  

   with 
  the 
  difference 
  of 
  the 
  horary 
  motions 
  in 
  declination, 
  denoting 
  the 
  

   quotient 
  by 
  q 
  ; 
  and 
  with 
  the 
  sun's 
  semidiameter, 
  denoting 
  the 
  quo- 
  

   tient 
  by 
  r. 
  With 
  the 
  moon's 
  declination, 
  as 
  a 
  course, 
  and 
  P' 
  as 
  a 
  dis- 
  

   tance, 
  enter 
  the 
  traverse 
  table, 
  and 
  faking 
  the 
  corresponding 
  difference 
  

   of 
  latitude, 
  mark 
  it 
  -j-, 
  and 
  denote 
  it 
  by 
  p'. 
  Then 
  will 
  q, 
  p\ 
  q 
  and 
  r, 
  

   respectively 
  express 
  the 
  difference 
  of 
  the 
  declinations, 
  the 
  difference 
  

   of 
  the 
  horary 
  motions 
  in 
  right 
  ascension, 
  the 
  difference 
  of 
  the 
  horary 
  

   motions 
  in 
  declination, 
  and 
  the 
  sun's 
  semidiameter, 
  in 
  such 
  parts 
  as 
  

   the 
  difference 
  of 
  the 
  parallaxes 
  contains 
  10; 
  the 
  difference 
  of 
  the 
  

   horary 
  motions 
  in 
  right 
  ascension 
  being 
  reduced 
  to 
  the 
  parallel 
  of 
  

   declination 
  passing 
  through 
  the 
  moon's 
  centre. 
  Letp 
  denote 
  the 
  dif- 
  

   ference 
  of 
  the 
  sun's 
  and 
  moon's 
  right 
  ascensions, 
  expressed 
  in 
  similar 
  

   parts, 
  and 
  reduced 
  to 
  the 
  same 
  parallel. 
  At 
  the 
  time 
  of 
  conjunction 
  

   in 
  right 
  ascension 
  p 
  = 
  0. 
  

  

  3. 
  Denote 
  the 
  Greenwich 
  mean 
  time 
  of 
  conjunction 
  in 
  right 
  ascen- 
  

   sion 
  by 
  T. 
  Find 
  from 
  the 
  Nautical 
  Almanac 
  the 
  corresponding 
  equa- 
  

   tion 
  of 
  time, 
  and 
  apply 
  it 
  to 
  T, 
  so 
  as 
  to 
  obtain 
  the 
  apparent 
  time. 
  To 
  

   the 
  apparent 
  time 
  apply 
  the 
  longitude 
  of 
  the 
  given 
  place 
  from 
  Green- 
  

   wich, 
  in 
  time, 
  by 
  adding 
  when 
  the 
  longitude 
  is 
  east, 
  but 
  subtracting 
  

   when 
  it 
  is 
  west, 
  and 
  convert 
  the 
  sum 
  or 
  remainder 
  into 
  degrees. 
  If 
  

   the 
  result 
  is 
  less 
  than 
  180°, 
  it 
  will 
  be 
  the 
  hour 
  angle 
  at 
  the 
  time 
  T, 
  

   and 
  will 
  be 
  -|-. 
  If 
  it 
  exceeds 
  180°, 
  subtract 
  it 
  from 
  360°, 
  and 
  the 
  

   remainder 
  will 
  be 
  the 
  hour 
  angle, 
  and 
  will 
  be 
  — 
  . 
  Denote 
  the 
  hour 
  

   angle 
  by 
  H, 
  

  

  With 
  the 
  sun's 
  declination 
  as 
  a 
  course, 
  and 
  the 
  value 
  of 
  Y 
  for 
  the 
  

   given 
  place 
  as 
  a 
  distance, 
  enter 
  the 
  traverse 
  table, 
  and 
  take 
  the 
  cor- 
  

   responding 
  difference 
  of 
  latitude, 
  marking 
  it 
  -j- 
  when 
  the 
  latitude 
  of 
  

   the 
  place 
  is 
  north, 
  but 
  — 
  when 
  it 
  is 
  south, 
  and 
  denote 
  it 
  by 
  h. 
  Take 
  

   also 
  the 
  departure, 
  marking 
  it 
  with 
  the 
  same 
  sign 
  as 
  the 
  declination 
  

   when 
  the 
  latitude 
  is 
  north, 
  but 
  with 
  a 
  contrary 
  sign 
  when 
  it 
  is 
  south, 
  

   and 
  denote 
  it 
  hyf. 
  

  

  4. 
  The 
  values 
  of 
  p', 
  q\ 
  r, 
  b, 
  and 
  /, 
  may 
  be 
  regarded 
  as 
  constant 
  

  

  