﻿256 
  

  

  Mr. 
  J. 
  B. 
  N. 
  Hennessey 
  on 
  the 
  [Feb. 
  11 
  

  

  when 
  again 
  reported 
  on, 
  the 
  sky 
  was 
  without 
  speck 
  or 
  cloud 
  ; 
  the 
  air 
  was 
  

   still, 
  and 
  so 
  clear, 
  so 
  brilliantly 
  clear, 
  that 
  even 
  the 
  most 
  exacting 
  of 
  

   observers 
  could 
  not 
  have 
  desired 
  more 
  favourable 
  circumstances 
  for 
  view- 
  

   ing 
  the 
  coming 
  transit. 
  In 
  brief, 
  I 
  enjoyed 
  most 
  exquisitely 
  clear 
  weather 
  

   during 
  my 
  observations 
  — 
  such 
  weather 
  as 
  occurs 
  not 
  frequently 
  even 
  at 
  

   Mussoorie. 
  

  

  I 
  now 
  proceed 
  to 
  describe 
  the 
  phenomena 
  of 
  the 
  transit. 
  In 
  doing 
  so 
  

   I 
  shall 
  have 
  occasion 
  to 
  speak 
  of 
  Venus 
  as 
  she 
  appeared 
  across 
  the 
  sun's 
  

   limb, 
  when 
  one 
  portion 
  of 
  her 
  own 
  limb 
  is 
  seen 
  against 
  the 
  sun, 
  and 
  the 
  

   other 
  remains 
  against 
  the 
  sky. 
  The 
  former 
  portion 
  I 
  shall 
  call 
  Yenus's 
  

   sun-limb, 
  or 
  V 
  n 
  , 
  the 
  latter 
  Yenus's 
  sky-limb, 
  or 
  Y 
  k 
  . 
  Again, 
  I 
  shall 
  require 
  

   to 
  mention 
  a 
  ring 
  of 
  light 
  around 
  Y 
  k 
  , 
  which 
  I 
  shall 
  indicate 
  by 
  L 
  k 
  , 
  the 
  

   corresponding 
  ring 
  around 
  Y 
  n 
  being 
  understood 
  by 
  L 
  n 
  . 
  Another 
  point 
  is 
  

   this 
  : 
  any 
  one 
  who 
  has 
  watched, 
  say 
  the 
  sun's 
  limb, 
  especially 
  at 
  a 
  low 
  

   altitude 
  and 
  with 
  high 
  power, 
  must 
  be 
  aware 
  of 
  the 
  turmoil 
  or 
  ebullition 
  

   which 
  there 
  appears, 
  very 
  much 
  as 
  if 
  the 
  limb 
  was 
  being 
  boiled. 
  I 
  shall 
  

   denote 
  this 
  kind 
  of 
  turmoil 
  by 
  " 
  boiling." 
  

  

  Ingress. 
  — 
  With 
  the 
  telescope 
  well 
  and 
  carefully 
  adjusted 
  for 
  focus, 
  I 
  

   watched 
  for 
  the 
  coming 
  first 
  external 
  contact, 
  but 
  to 
  no 
  purpose 
  ; 
  for 
  I 
  

   did 
  not 
  detect 
  Yenus's 
  limb 
  until 
  after 
  it 
  had 
  made 
  an 
  indentation 
  on 
  the 
  

   sun's 
  limb. 
  The 
  latter 
  boiled 
  sensibly, 
  but 
  by 
  no 
  means 
  violently. 
  It 
  

   appeared 
  jagged, 
  and 
  as 
  if 
  with 
  minute 
  spikes 
  projecting 
  inwards, 
  all 
  of 
  

   which 
  were 
  well 
  defined 
  in 
  the 
  bluish 
  field. 
  "Watching 
  Y 
  n 
  , 
  I 
  f 
  oimd 
  it 
  also 
  

   boiling 
  slightly, 
  but 
  in 
  a 
  manner 
  somewhat 
  different 
  to 
  the 
  sun's 
  limb. 
  

   The 
  appearance 
  was 
  that 
  of 
  boiling 
  vapour 
  coming 
  round 
  from 
  the 
  face 
  of 
  

   Yenus, 
  turned 
  towards 
  the 
  sun 
  and 
  overlapping 
  Y 
  n 
  ; 
  moreover 
  this 
  boil- 
  

   ing 
  was 
  not 
  restricted 
  to 
  the 
  edge 
  of 
  Y 
  n 
  , 
  but 
  extended 
  2" 
  or 
  3" 
  beyond, 
  

   thus 
  forming 
  a 
  kind 
  of 
  boiling 
  annulus*, 
  in 
  which 
  there 
  were 
  minute 
  

   sparkling 
  specks 
  dancing 
  and 
  shifting 
  about, 
  appearing 
  and 
  disappearing 
  ; 
  

   the 
  edge 
  Y 
  n 
  was 
  seen 
  through 
  the 
  boiling. 
  So 
  much 
  for 
  that 
  portion 
  of 
  

   Yenus 
  seen 
  against 
  the 
  sun. 
  

  

  Ingress 
  (continued). 
  — 
  At 
  8^ 
  minutes 
  before 
  the 
  first 
  internal 
  contact 
  

   took 
  place, 
  I 
  happened 
  to 
  look 
  closely 
  into 
  the 
  spot 
  where 
  that 
  part 
  of 
  

   Yenus 
  against 
  the 
  sky 
  lay 
  ; 
  and, 
  to 
  my 
  great 
  surprise, 
  I 
  found 
  that 
  this 
  

   portion 
  of 
  her 
  disk 
  was 
  easily 
  visible, 
  because 
  it 
  was 
  edged 
  by 
  a 
  narrow 
  

   ring 
  of 
  light, 
  or 
  L 
  k 
  . 
  At 
  first 
  I 
  saw 
  L 
  k 
  for 
  only 
  about 
  10° 
  or 
  15° 
  on 
  either 
  

   side 
  of 
  the 
  point 
  where 
  the 
  chord 
  of 
  Yenus's 
  track 
  would 
  cut 
  Y 
  k 
  — 
  or, 
  more 
  

   definitely 
  stated, 
  this 
  light-ring 
  did 
  not 
  reach 
  either 
  way 
  to 
  the 
  sun's 
  

   limb 
  ; 
  but 
  within 
  the 
  next 
  50 
  s 
  I 
  saw 
  the 
  ring 
  distinctly 
  round 
  the 
  whole 
  

   sector 
  of 
  Y 
  k 
  , 
  from 
  edge 
  to 
  edge 
  of 
  the 
  sun's 
  limb, 
  as 
  shown 
  in 
  the 
  rough 
  

   sketch 
  t 
  accompanying. 
  The 
  light-ring 
  was 
  only 
  moderately 
  bright, 
  like 
  

  

  * 
  This 
  cannot 
  be 
  shown 
  in 
  the 
  sketch 
  accompanying, 
  for 
  its 
  presence 
  became 
  visible 
  

   chiefly 
  through 
  the 
  movements 
  taking 
  place. 
  

  

  t 
  I 
  must 
  apologize 
  for 
  the 
  roughness 
  of 
  my 
  sketch. 
  I 
  am, 
  however, 
  writing 
  against 
  

   time 
  to 
  catch 
  the 
  outgoing 
  mail 
  ; 
  and 
  of 
  drawing-materials 
  I 
  possess 
  nothing 
  more 
  at 
  

  

  