﻿254 
  

  

  Mr. 
  J. 
  B. 
  N. 
  Hennessey 
  on 
  the 
  

  

  [Feb. 
  11, 
  

  

  body-cavity 
  of 
  the 
  Planula. 
  It 
  is 
  only 
  just 
  before 
  the 
  escape 
  of 
  the 
  

   actinuloid 
  from 
  its 
  capsule 
  that 
  they 
  evaginate 
  themselves 
  and 
  become 
  

   external. 
  

  

  After 
  enjoying 
  its 
  free 
  existence 
  for 
  one 
  or 
  two 
  days, 
  during 
  which 
  

   it 
  moves 
  about 
  by 
  the 
  aid 
  of 
  its 
  long 
  arms, 
  the 
  embryo 
  fixes 
  itself 
  by 
  

   its 
  proximal 
  end, 
  the 
  long 
  arms 
  gradually 
  disappear, 
  the 
  short 
  permanent 
  

   tentacles 
  increase 
  in 
  number, 
  and 
  the 
  essential 
  form 
  of 
  the 
  adult 
  is 
  soon 
  

   acquired. 
  

  

  II, 
  " 
  Some 
  Particulars 
  of 
  the 
  Transit 
  of 
  Venus 
  across 
  the 
  Sun, 
  

   December 
  9, 
  1874, 
  observed 
  on 
  the 
  Himalaya 
  Mountains, 
  

   Mussoorie, 
  at 
  May-Villa 
  Station, 
  Lat. 
  30° 
  28' 
  N., 
  Long. 
  

   78° 
  3' 
  E., 
  Height 
  above 
  Sea 
  6765 
  feet/'— 
  Note 
  No. 
  I. 
  By 
  

   J. 
  B. 
  N. 
  Hennessey, 
  F.R.A.S. 
  Communicated 
  by 
  Prof. 
  

   Stokes, 
  D.C.L., 
  Sec. 
  U.S. 
  Beceived 
  January 
  2, 
  1875. 
  

  

  May 
  Yilla, 
  9th 
  December, 
  1874. 
  

  

  Naturally 
  sharing 
  in 
  the 
  great 
  interest 
  excited 
  by 
  the 
  transit 
  of 
  Venus, 
  

   which 
  occurred 
  this 
  forenoon, 
  I 
  proposed 
  that 
  I 
  should 
  observe 
  the 
  event 
  

   with 
  the 
  equatoreal 
  of 
  the 
  Boyal 
  Society, 
  which 
  Capt. 
  J. 
  Herschel, 
  B.E., 
  

   in 
  his 
  absence 
  from 
  India, 
  had 
  temporarily 
  placed 
  at 
  my 
  disposal 
  ; 
  and 
  the 
  

   project 
  meeting 
  with 
  liberal 
  support 
  from 
  Col. 
  J. 
  T. 
  Walker, 
  B.E., 
  

   Superintendent, 
  Great 
  Trigonometrical 
  Survey 
  of 
  India, 
  I 
  was 
  enabled, 
  

   through 
  his 
  kindness, 
  to 
  provide 
  myself 
  with 
  four 
  chronometers, 
  a 
  good 
  

   altazimuth, 
  a 
  barometer, 
  thermometers, 
  and 
  other 
  articles 
  of 
  equipment 
  

   necessary 
  for 
  the 
  undertaking. 
  My 
  especial 
  object 
  in 
  view 
  was 
  to 
  observe 
  

   the 
  transit 
  from 
  a 
  considerable 
  height; 
  and 
  this 
  condition 
  was 
  easily 
  

   secured 
  through 
  the 
  circumstance 
  that 
  I 
  was 
  located 
  only 
  14 
  miles 
  from 
  

   Mussoorie, 
  on 
  the 
  Himalaya 
  Mountains. 
  No 
  doubt 
  a 
  station 
  on 
  these 
  

   mountains 
  would 
  be 
  very 
  liable 
  to 
  an 
  envelope 
  of 
  mist 
  and 
  cloud 
  at 
  the 
  

   time 
  of 
  year 
  in 
  question 
  ; 
  but, 
  on 
  the 
  other 
  hand, 
  were 
  really 
  good 
  weather 
  

   to 
  prevail, 
  I 
  should 
  enjoy 
  the 
  advantages 
  of 
  an 
  exquisitely 
  clear 
  atmo- 
  

   sphere, 
  such 
  as 
  I. 
  have 
  never 
  experienced 
  save 
  on 
  the 
  Himalayas. 
  Add 
  

   to 
  this, 
  the 
  journey, 
  as 
  already 
  stated, 
  was 
  merely 
  an 
  ordinary 
  ride, 
  the 
  

   necessary 
  equipment 
  for 
  my 
  purpose 
  was 
  at 
  hand, 
  and 
  though 
  failure 
  

   would 
  involve 
  a 
  waste 
  of 
  no 
  inconsiderable 
  preliminary 
  labour, 
  this 
  latter 
  

   I 
  was 
  willing 
  to 
  incur 
  if 
  need 
  be. 
  Arguing 
  thus, 
  I 
  selected 
  a 
  station 
  some 
  

   6500 
  feet 
  above 
  the 
  sea, 
  and 
  proceeded 
  to 
  find 
  my 
  latitude, 
  longitude, 
  and 
  

   height, 
  to 
  observe 
  for 
  time, 
  and 
  to 
  rate 
  my 
  chronometers. 
  My 
  numerical 
  

   results 
  will 
  be 
  communicated 
  very 
  shortly 
  in 
  a 
  second 
  note. 
  The 
  remarks 
  

   here 
  made 
  are 
  restricted 
  chiefly 
  to 
  what 
  I 
  saw 
  with 
  the 
  equatoreal. 
  

  

  The 
  telescope 
  of 
  the 
  equatoreal 
  has 
  a 
  5-inch 
  object-glass, 
  with 
  about 
  

   60 
  inches 
  focal 
  length, 
  and 
  is 
  driven 
  by 
  an 
  excellent 
  clock. 
  The 
  eye-end 
  

   may 
  be 
  fitted 
  at 
  will 
  with 
  an 
  eyepiece 
  of 
  55, 
  85, 
  125, 
  200, 
  or 
  300 
  power, 
  

  

  