﻿SOLAR 
  ECLIPSE 
  OF 
  NOVEMBER 
  SO, 
  1834. 
  243 
  

  

  h. 
  m. 
  sec. 
  

  

  49 
  52 
  Commencement 
  of 
  eclipse. 
  

  

  2 
  14 
  00 
  Greatest 
  obscuration. 
  

  

  3 
  30 
  52 
  End 
  of 
  eclipse. 
  

  

  The 
  v. 
  sine 
  of 
  crescent 
  measured 
  by 
  257 
  divisions 
  of 
  micrometer 
  scale, 
  the 
  value 
  of 
  

   each 
  division 
  being 
  .45191" 
  or 
  45". 
  191 
  to 
  each 
  thread 
  of 
  the 
  screw. 
  

  

  The 
  foregoing; 
  observations 
  for 
  time 
  were 
  made 
  by 
  setting 
  the 
  teles- 
  

   cope 
  of 
  the 
  circle, 
  and 
  taking 
  the 
  transit 
  of 
  the 
  sun's 
  first 
  limb, 
  and 
  

   then 
  reversed. 
  It 
  was 
  thought 
  that 
  the 
  interval, 
  if 
  both 
  limbs 
  were 
  

   observed, 
  would 
  be 
  too 
  great 
  to 
  allow 
  of 
  taking 
  an 
  arithmetical 
  mean 
  

   for 
  the 
  time. 
  The 
  second 
  limb 
  was 
  taken 
  after 
  reversing 
  in 
  all 
  but 
  

   the 
  first 
  morning 
  observation, 
  when 
  the 
  first 
  limb 
  was 
  observed 
  before 
  

   and 
  after 
  reversing. 
  

  

  To 
  correct, 
  if 
  necessary, 
  any 
  inequality 
  in 
  the 
  rate 
  of 
  the 
  pocket 
  

   chronometer, 
  in 
  the 
  correctness 
  of 
  which 
  I 
  had 
  little 
  confidence, 
  as 
  it 
  

   was 
  habitually 
  used 
  as 
  a 
  pocket 
  watch, 
  I 
  compared 
  it 
  about 
  every 
  hour 
  

   with 
  the 
  clock, 
  which 
  was 
  set 
  going 
  for 
  the 
  occasion. 
  The 
  rate 
  of 
  the 
  

   clock 
  could 
  be 
  depended 
  upon 
  for 
  uniformity, 
  but 
  what 
  that 
  was, 
  was 
  

   unknown, 
  as 
  it 
  had 
  been 
  moved 
  in 
  the 
  interval 
  of 
  my 
  absence, 
  and 
  

   there 
  was 
  no 
  opportunity, 
  owing 
  to 
  the 
  bad 
  weather, 
  of 
  ascertaining 
  

   the 
  true 
  time 
  or 
  rate 
  until 
  Sunday 
  the 
  day 
  of 
  the 
  eclipse. 
  

  

  Comparison 
  of 
  clock 
  and 
  chronometer 
  : 
  — 
  

  

  

  h. 
  m. 
  sec. 
  

  

  h. 
  m. 
  sec. 
  

  

  h. 
  m. 
  sec. 
  

  

  h. 
  m. 
  sec. 
  

  

  Clock, 
  

  

  20 
  41 
  00 
  

  

  21 
  28 
  00 
  

  

  22 
  28 
  00 
  

  

  24 
  00 
  00 
  

  

  Chron. 
  

  

  20 
  22 
  10.13 
  

  

  21 
  09 
  08.13 
  

  

  22 
  09 
  05.6 
  

  

  23 
  41 
  01.07 
  

  

  Clock, 
  

  

  00 
  45 
  00 
  

  

  1 
  45 
  00 
  

  

  3 
  05 
  00 
  

  

  4 
  19 
  00 
  

  

  Chron. 
  

  

  00 
  25 
  58.4 
  

  

  1 
  25 
  56 
  

  

  2 
  45 
  52 
  

  

  3 
  59 
  48.5 
  

  

  In 
  addition 
  to 
  the 
  foregoing 
  observations, 
  the 
  following 
  measure- 
  

   ments 
  were 
  made 
  of 
  the 
  chord 
  of 
  the 
  obscured 
  segment 
  of 
  the 
  sun 
  

   with 
  a 
  spider's 
  line 
  micrometer. 
  The 
  telescope 
  to 
  which 
  it 
  was 
  applied 
  

   was 
  not 
  mounted 
  on 
  the 
  equatorial, 
  and 
  the 
  measurements 
  were 
  not 
  

   therefore 
  made 
  with 
  as 
  great 
  accuracy 
  as 
  they 
  could 
  have 
  been 
  under 
  

   more 
  favourable 
  circumstances. 
  They 
  are, 
  however, 
  appended, 
  that 
  

   they 
  may 
  be 
  examined 
  and 
  used 
  if 
  of 
  any 
  value. 
  The 
  value 
  of 
  the 
  

   micrometer, 
  as 
  before 
  stated, 
  is 
  .45191" 
  for 
  each 
  division. 
  By 
  taking 
  

   a 
  mean 
  of 
  several 
  measurements 
  of 
  the 
  sun's 
  diameter 
  when 
  on 
  or 
  near 
  

   the 
  meridian, 
  say 
  .452". 
  

  

  