﻿244 
  

  

  COLLECTION 
  OF 
  OBSERVATIONS 
  ON 
  THE 
  

  

  Time 
  by 
  Chronometer. 
  

  

  Div. 
  of 
  Micrometer. 
  

  

  Time 
  by 
  Chronometer. 
  

  

  Div. 
  of 
  Micrometer. 
  

  

  h. 
  m. 
  sec. 
  

  

  

  h. 
  m. 
  sec. 
  

  

  

  52 
  16.2 
  

  

  10S7 
  

  

  3 
  17 
  16.3 
  

  

  2516 
  

  

  53 
  20 
  

  

  128S 
  

  

  IS 
  OS 
  

  

  2451 
  

  

  54 
  20.2 
  

  

  1434 
  

  

  19 
  5S.4 
  

  

  2373 
  

  

  55 
  12 
  

  

  1530.5 
  

  

  20 
  36.3 
  

  

  2305 
  

  

  56 
  22.3 
  

  

  1701 
  

  

  21 
  34 
  

  

  2219 
  

  

  57 
  56 
  

  

  1844 
  

  

  23 
  38 
  

  

  1S92 
  

  

  5S 
  36.2 
  

  

  1931 
  

  

  24 
  22 
  

  

  1S27 
  

  

  59 
  36.2 
  

  

  2040 
  

  

  25 
  OS 
  

  

  1724 
  

  

  1 
  00 
  OS. 
  4 
  

  

  2095 
  

  

  25 
  56 
  

  

  1616 
  

  

  04 
  5S.4 
  

  

  2489 
  

  

  26 
  30 
  

  

  1520 
  

  

  05 
  42.3 
  

  

  2543 
  

  

  27 
  0S.4 
  

  

  1409 
  

  

  13 
  5S.4 
  

  

  3064 
  

  

  2S 
  10 
  

  

  1241 
  

  

  14 
  44 
  

  

  3102 
  

  

  28 
  52 
  

  

  1053 
  

  

  3 
  13 
  00 
  

  

  2839 
  

  

  29 
  13 
  

  

  946 
  

  

  14 
  16,2 
  

  

  2750 
  

  

  29 
  42.4 
  

  

  792 
  

  

  15 
  30 
  

  

  2647 
  

  

  30 
  26 
  

  

  502 
  

  

  16 
  26 
  

  

  25S0 
  

  

  

  

  The 
  following 
  measurements 
  were 
  made 
  of 
  the 
  versed 
  sines 
  of 
  the 
  

   unobscured 
  part 
  of 
  the 
  sun's 
  disk. 
  The 
  difficulty 
  of 
  measuring 
  Jhese 
  

   accurately, 
  was 
  much 
  greater 
  than 
  of 
  measuring 
  the 
  chords 
  ; 
  in 
  those 
  

   the 
  perpendicular 
  hair 
  could 
  be 
  made 
  to 
  coincide 
  with 
  the 
  angles 
  of 
  

   the 
  disk, 
  and 
  there 
  was 
  no 
  doubt 
  of 
  the 
  measured 
  line 
  being 
  perpen- 
  

   dicular 
  to 
  the 
  parallel 
  lines 
  of 
  the 
  micrometer. 
  In 
  measuring 
  the 
  

   versed 
  sines, 
  the 
  eye 
  alone 
  could 
  decide, 
  except 
  so 
  far 
  as 
  it 
  could 
  be 
  

   aided 
  by 
  first 
  bringing 
  the 
  perpendicular 
  line 
  to 
  coincide 
  with 
  the 
  

   angular 
  points, 
  and 
  then 
  moving 
  the 
  telescope 
  in 
  azimuth 
  to 
  bring 
  the 
  

   parallel 
  wires 
  on 
  the 
  concave 
  and 
  convex 
  parts 
  of 
  the 
  crescent; 
  but 
  

   this 
  line 
  changed 
  its 
  angle 
  with 
  the 
  horizon 
  so 
  rapidly, 
  that 
  little 
  assist- 
  

   ance 
  could 
  be 
  derived 
  from 
  this 
  practice. 
  

  

  Time 
  by 
  Chronometer. 
  

  

  Div. 
  of 
  Micrometer. 
  

  

  h. 
  m. 
  sec. 
  

  

  

  1 
  17 
  40 
  

  

  2915 
  

  

  21 
  12 
  

  

  2762 
  

  

  33 
  18 
  

  

  2150 
  

  

  39 
  28 
  

  

  1833 
  

  

  4S 
  16 
  

  

  13S1 
  

  

  50 
  28 
  

  

  1263 
  

  

  2 
  OS 
  4S 
  

  

  378 
  

  

  14 
  00 
  

  

  257 
  

  

  20 
  24 
  

  

  431 
  

  

  33 
  02 
  

  

  1050 
  

  

  41 
  47 
  

  

  1531 
  

  

  3 
  06 
  04 
  

  

  2S21 
  

  

  09 
  46 
  

  

  3011 
  

  

  