﻿[25] 
  REPORT 
  ON 
  THERMOMETERS. 
  209 
  

  

  space 
  through 
  which 
  the 
  thermometer 
  should 
  pass 
  before 
  turning 
  over 
  

   must 
  be 
  regulated 
  at 
  starting. 
  If 
  the 
  instrument 
  ascends 
  a 
  few 
  feet 
  by 
  

   reason 
  of 
  a 
  stoppage 
  of 
  the 
  line 
  while 
  attaching 
  other 
  thermometers, 
  or 
  

   through 
  the 
  heave 
  of 
  the 
  sea, 
  or 
  any 
  cause 
  whatever, 
  the 
  subsequent 
  

   descent 
  will 
  cause 
  the 
  fan 
  to 
  carry 
  back 
  the 
  stop 
  to 
  its 
  initial 
  position, 
  

   and 
  such 
  stoppages 
  may 
  occur 
  any 
  number 
  of 
  times 
  provided 
  the 
  line 
  

   is 
  not 
  made 
  to 
  ascend 
  through 
  the 
  space 
  necessary 
  to 
  cause 
  the 
  fan 
  to 
  

   release 
  the 
  thermometer. 
  When 
  the 
  hauling-in 
  has 
  caused 
  the 
  turn 
  

   over 
  of 
  the 
  thermometer, 
  the 
  lateral 
  spring 
  K 
  forces 
  the 
  spring 
  L 
  into 
  

   a 
  slot 
  in 
  the 
  case 
  B 
  and 
  clamps 
  it 
  until 
  it 
  is 
  received 
  on 
  board, 
  so 
  that 
  

   no 
  change 
  of 
  position 
  can 
  occur 
  iu 
  the 
  rest 
  of 
  the 
  ascent 
  from 
  any 
  cause. 
  

   The 
  case 
  B 
  is 
  cut 
  open 
  to 
  expose 
  the 
  scale 
  of 
  the 
  thermometer, 
  and 
  is 
  

   also 
  perforated 
  to 
  allow 
  the 
  free 
  entry 
  of 
  the 
  water. 
  

  

  ''The 
  construction 
  of 
  the 
  thermometer 
  will 
  be 
  uiulerstood 
  by 
  reference 
  

   to 
  the 
  figure. 
  The 
  bulb 
  is 
  cylindrical, 
  and 
  mercury 
  is 
  thethermometri- 
  

   cal 
  fluid. 
  The 
  neck 
  of 
  the 
  bulb 
  is 
  contracted 
  at 
  A, 
  and 
  upon 
  the 
  shape 
  

   and 
  fineness 
  of 
  this 
  contraction 
  the 
  success 
  of 
  the 
  instrument 
  depends. 
  

   Beyond 
  A 
  the 
  tube 
  is 
  bent, 
  and 
  a 
  small 
  reservoir 
  is 
  formed 
  at 
  B. 
  At 
  

   the 
  end 
  of 
  the 
  tube 
  a 
  small 
  receptacle, 
  C, 
  is 
  provided. 
  When 
  the 
  bulb 
  

   is 
  downward 
  it 
  contains 
  sufficient 
  mercury 
  to 
  fill 
  the 
  tube, 
  and 
  a 
  part 
  

   of 
  the 
  reservoir 
  C, 
  if 
  the 
  temperature 
  is 
  high, 
  leaving 
  sufficient 
  space 
  

   for 
  the 
  expansion 
  of 
  the 
  mercury. 
  In 
  this 
  position 
  no 
  scale 
  would 
  be 
  

   possible, 
  as 
  the 
  apparent 
  movement 
  of 
  the 
  mercury 
  would 
  be 
  confined 
  

   to 
  the 
  space 
  C. 
  When 
  the 
  thermometer 
  is 
  held 
  bulb 
  upward, 
  the 
  

   mercury 
  breaks 
  off 
  at 
  A, 
  and 
  by 
  its 
  own 
  weight 
  flows 
  down 
  the 
  tube, 
  

   filling 
  C, 
  and 
  a 
  portion 
  of 
  the 
  tube 
  above. 
  The 
  scale 
  accordingly 
  is 
  

   made 
  to 
  read 
  upward 
  from 
  C. 
  To 
  set 
  the 
  thermometer 
  for 
  observation 
  

   it 
  is 
  only 
  necessary 
  to 
  place 
  it 
  bulb 
  downward, 
  then 
  the 
  mercury 
  takes 
  

   the 
  temperature 
  just 
  as 
  an 
  ordinary 
  thermometer. 
  Whenever 
  the 
  exist- 
  

   ing 
  temperature 
  is 
  required, 
  all 
  that 
  has 
  to 
  be 
  done 
  is 
  to 
  turn 
  the 
  ther- 
  

   mometer 
  bulb 
  upward 
  and 
  keep 
  it 
  in 
  this 
  position 
  until 
  read 
  off. 
  The 
  

   reading 
  may 
  be 
  taken 
  any 
  time 
  after." 
  

  

  To 
  insure 
  the 
  prompt 
  reversal 
  of 
  this 
  instrument, 
  which 
  was 
  found 
  

   sometimes 
  to 
  stick, 
  an 
  india-rubber 
  band 
  was 
  applied 
  during 
  the 
  cruise 
  

   of 
  the 
  Triton, 
  in 
  the 
  summer 
  of 
  1882.* 
  

  

  In 
  the 
  voyage 
  of 
  the 
  Talisman 
  a 
  frame 
  was 
  used 
  " 
  construit 
  rVapres 
  les 
  

   indication* 
  do 
  M. 
  Alphouse 
  Milne-Ed 
  wards,"t 
  which 
  closely 
  resembled 
  

   the 
  Maguaghi 
  frames 
  without 
  the 
  revolving 
  propeller. 
  The 
  detaching 
  

   apparatus 
  consisted 
  iu 
  a 
  lever 
  attached 
  to 
  the 
  sounding 
  weight 
  by 
  a 
  

   light 
  hempen 
  string, 
  and 
  holding 
  the 
  thermometer 
  in 
  place. 
  When 
  the 
  

   weight 
  was 
  released 
  the 
  lever 
  was 
  pulled 
  down 
  by 
  the 
  string, 
  setting 
  

   the 
  thermometer 
  free 
  to 
  the 
  action 
  of 
  a 
  spring, 
  which 
  caused 
  it 
  to 
  over- 
  

  

  * 
  Challenger 
  Narrativo, 
  vol. 
  1, 
  part 
  first, 
  page 
  95. 
  

  

  t 
  Explorations 
  Sous-Marines. 
  Voyage 
  du 
  Talisman. 
  H. 
  Filhol, 
  in 
  La 
  Nature, 
  

   No. 
  55(3, 
  January, 
  1884, 
  page 
  135. 
  

   S. 
  Mis. 
  70 
  14 
  

  

  