﻿1875.] 
  

  

  Transit 
  of 
  Venus 
  across 
  the 
  Sun. 
  

  

  255 
  

  

  or 
  with 
  a 
  spectroscope 
  mounting 
  a 
  single 
  simple 
  prism. 
  The 
  polar 
  axis 
  

   may 
  be 
  shifted 
  for 
  latitude. 
  The 
  equatoreal 
  was 
  set 
  up 
  and 
  adjusted 
  

   in 
  an 
  observatory-tent, 
  of 
  which 
  the 
  canvas 
  top 
  was 
  removed 
  during 
  

   observation. 
  

  

  I 
  found 
  from 
  actual 
  trial 
  that 
  the 
  most 
  suitable 
  eyepiece 
  for 
  both 
  

   ingress 
  (sun's 
  altitude 
  2° 
  24' 
  to 
  7° 
  29') 
  and 
  egress 
  (sun's 
  altitude 
  about 
  

   26°) 
  was 
  that 
  of 
  125 
  power 
  ; 
  accordingly 
  this 
  eyepiece 
  alone 
  was 
  employed 
  

   at 
  the 
  contacts. 
  It 
  was, 
  however, 
  impossible 
  to 
  adopt 
  the 
  same 
  dark 
  glass 
  

   for 
  both 
  the 
  higher 
  and 
  lower 
  altitudes, 
  without 
  sacrificing 
  definition 
  on 
  

   one 
  of 
  the 
  two 
  occasions. 
  Accordingly 
  I 
  selected 
  for 
  ingress 
  two 
  glasses 
  

   which, 
  combined, 
  gave 
  a 
  neutral 
  or 
  bluish 
  field 
  ; 
  and 
  for 
  egress 
  I 
  changed 
  

   one 
  of 
  these 
  for 
  a 
  deep-red 
  glass, 
  so 
  that 
  the 
  field 
  now 
  presented 
  a 
  mode- 
  

   rately 
  deep 
  red. 
  The 
  glasses 
  were 
  quite 
  flat, 
  and 
  lay 
  against 
  one 
  another 
  

   in 
  intimate 
  contact, 
  giving 
  excellent 
  definition. 
  I 
  may 
  here 
  add 
  that, 
  

   thanks 
  to 
  Manrakan, 
  artificer, 
  Gr. 
  T. 
  Survey, 
  the 
  clock 
  behaved 
  with 
  per- 
  

   fect 
  regularity 
  ; 
  nor 
  was 
  there 
  the 
  smallest 
  instrumental 
  disappointment 
  

   throughout 
  the 
  work. 
  As 
  regards 
  procedure 
  during 
  transit, 
  my 
  friend 
  

   Mr. 
  W. 
  H. 
  Cole, 
  M.A., 
  counted 
  seconds 
  audibly 
  from 
  the 
  journeyman 
  

   chronometer 
  placed 
  before 
  him 
  ; 
  while 
  Baboo 
  Cally 
  Mohun 
  Grhose, 
  com- 
  

   puter, 
  took 
  up 
  a 
  position 
  by 
  my 
  side, 
  noting 
  down 
  such 
  remarks 
  as 
  the 
  

   phenomena, 
  viewed 
  through 
  the 
  equatoreal, 
  elicited 
  from 
  me. 
  Nor, 
  as 
  

   we 
  stood 
  informed, 
  were 
  the 
  events 
  to 
  be 
  recorded 
  few 
  in 
  number. 
  At, 
  

   for 
  instance, 
  ingress, 
  internal 
  contact, 
  the 
  light 
  between 
  the 
  cusps 
  was 
  

   to 
  vary 
  suddenly 
  ; 
  the 
  cusps 
  were 
  to 
  meet. 
  Then 
  came 
  " 
  the 
  pear-drop," 
  

   " 
  the 
  ligament 
  ; 
  " 
  what 
  should 
  be 
  its 
  length, 
  what 
  its 
  breadth 
  in 
  terms 
  of 
  

   Yenus's 
  diameter, 
  what 
  its 
  shape? 
  when 
  would 
  it 
  break? 
  and, 
  lastly, 
  which 
  

   of 
  the 
  known 
  descriptions 
  would 
  it 
  resemble 
  ? 
  Primed 
  on 
  these 
  points, 
  

   we 
  settled 
  on 
  a 
  programme 
  which 
  should 
  include 
  them 
  all, 
  and 
  time 
  after 
  

   time 
  we 
  went 
  through 
  the 
  necessary 
  rehearsals 
  for 
  perfecting 
  ourselves 
  in 
  

   our 
  parts. 
  So 
  much 
  for 
  what 
  w 
  T 
  e 
  had 
  to 
  expect, 
  and 
  now 
  for 
  a 
  few 
  words 
  

   on 
  the 
  weather. 
  

  

  I 
  moved 
  up 
  to 
  my 
  mountain-station 
  on 
  the 
  afternoon 
  of 
  December 
  1. 
  

   The 
  day 
  following 
  I 
  was 
  busy 
  fixing 
  my 
  station, 
  adjusting 
  instruments, 
  

   &c. 
  Up 
  to 
  this 
  the 
  sky 
  had 
  been 
  sufficiently 
  clear 
  ; 
  but 
  from 
  the 
  3rd 
  

   there 
  set 
  in 
  an 
  alternation 
  of 
  weather, 
  which, 
  without 
  running 
  into 
  

   extremes, 
  kept 
  me 
  in 
  a 
  state 
  of 
  miserable 
  suspense, 
  to 
  say 
  nothing 
  of 
  the 
  

   additional 
  watching 
  and 
  toil 
  in 
  observing 
  for 
  time. 
  This 
  state 
  of 
  affairs 
  

   appeared 
  drawing 
  to 
  a 
  climax, 
  when 
  the 
  8th 
  December 
  arrived, 
  and 
  the 
  

   clouds 
  looked 
  blacker, 
  while 
  the 
  mist, 
  which 
  generally 
  precedes 
  snowfalls 
  

   here, 
  began 
  as 
  usual 
  to 
  settle 
  down 
  on 
  the 
  internal 
  and 
  still 
  more 
  lofty 
  

   ranges 
  of 
  hills. 
  About 
  2 
  p.m. 
  on 
  this 
  day 
  there 
  were 
  a 
  few 
  drops 
  of 
  rain 
  

   or 
  sleet, 
  so 
  few 
  that 
  they 
  might 
  almost 
  have 
  been 
  counted 
  ; 
  and 
  later 
  on, 
  

   as 
  the 
  sun 
  began 
  to 
  set, 
  the 
  heavy 
  cumuli 
  evolved 
  themselves 
  into 
  strati, 
  

   w 
  r 
  hich, 
  spreading 
  their 
  even 
  canopy 
  over 
  us, 
  left 
  something 
  like 
  decimal 
  

   of 
  sky 
  visible 
  ; 
  and 
  this 
  at 
  10 
  o'clock 
  at 
  night 
  ! 
  At 
  4 
  next 
  morning, 
  Dec. 
  9, 
  

  

  