﻿302 
  

  

  Mr. 
  J. 
  Y. 
  Buchanan 
  on 
  the 
  

  

  [Mar. 
  4, 
  

  

  its 
  temperature 
  ; 
  and 
  fourth, 
  the 
  reduction 
  of 
  the 
  results 
  to 
  their 
  value 
  

   at 
  a 
  common 
  temperature. 
  These 
  divisions 
  of 
  the 
  subject 
  are 
  treated 
  

   in 
  their 
  order. 
  

  

  The 
  samples 
  of 
  water 
  are 
  collected 
  either 
  in 
  an 
  ordinary 
  canvas 
  bucket 
  

   or 
  in 
  one 
  of 
  two 
  kinds 
  of 
  metal 
  " 
  water-bottle/' 
  according 
  as 
  it 
  is 
  to 
  be 
  

   taken 
  from 
  the 
  surface 
  or 
  from 
  depths 
  below 
  it. 
  The 
  use 
  of 
  the 
  ordinary 
  

   hand-bucket 
  needs 
  no 
  explanation. 
  "When 
  water 
  is 
  to 
  be 
  obtained 
  from 
  

   the 
  bottom, 
  the 
  " 
  slip 
  " 
  water-bottle 
  is 
  used. 
  This 
  instrument 
  is 
  a 
  

   Swedish 
  invention, 
  improved 
  by 
  Dr. 
  Meyer, 
  of 
  Kiel, 
  who 
  without 
  doubt 
  

   has 
  described 
  it, 
  and 
  by 
  Messrs. 
  Milne, 
  of 
  Edinburgh, 
  who 
  furnished 
  those 
  

   used 
  on 
  board 
  the 
  ' 
  Challenger.' 
  

  

  "Water 
  from 
  intermediate 
  depths 
  is 
  obtained 
  in 
  a 
  much 
  lighter 
  instru- 
  

   ment, 
  which, 
  with 
  a 
  drawing 
  and 
  the 
  method 
  of 
  using 
  it, 
  is 
  fully 
  described 
  

   in 
  the 
  paper 
  of 
  which 
  this 
  is 
  an 
  abstract. 
  In 
  principle 
  it 
  consists 
  of 
  a 
  

   metal 
  cylinder 
  furnished 
  with 
  stopcocks 
  at 
  both 
  ends. 
  The 
  levers 
  by 
  

   which 
  these 
  stopcocks 
  are 
  turned 
  are 
  connected 
  by 
  a 
  straight 
  rod, 
  so 
  that 
  

   they 
  are 
  simultaneously 
  either 
  open 
  or 
  shut, 
  or 
  at 
  least 
  at 
  the 
  same 
  phase 
  

   of 
  being 
  open 
  or 
  shut. 
  When 
  water 
  is 
  to 
  be 
  collected 
  by 
  its 
  means, 
  the 
  

   stopcocks 
  are 
  opened 
  and 
  the 
  instrument 
  sunk 
  to 
  the 
  required 
  depth, 
  

   having 
  been 
  previously 
  securely 
  fastened 
  to 
  a 
  sounding-line. 
  The 
  opera- 
  

   tion 
  of 
  sinking 
  must 
  be 
  carried 
  on 
  without 
  a 
  check, 
  owing 
  to 
  the 
  pecu- 
  

   liarity 
  of 
  the 
  closing-apparatus. 
  When 
  the 
  required 
  depth 
  has 
  been 
  

   reached, 
  the 
  line 
  is 
  checked, 
  hauled 
  in 
  a 
  few 
  fathoms, 
  let 
  go 
  again, 
  and 
  

   finally 
  brought 
  to 
  the 
  surface 
  by 
  means 
  of 
  the 
  donkey-engine. 
  The 
  rod 
  

   connecting 
  the 
  stopcocks 
  is 
  furnished 
  with 
  a 
  metal 
  plate, 
  which, 
  during 
  

   the 
  descent, 
  is 
  retained 
  in 
  a 
  vertical 
  position 
  by 
  the 
  passage 
  of 
  the 
  water 
  

   on 
  both 
  sides 
  of 
  it. 
  When, 
  however, 
  the 
  direction 
  of 
  motion 
  is 
  reversed, 
  

   the 
  plate 
  falls 
  down 
  into 
  a 
  horizontal 
  position, 
  when, 
  by 
  its 
  passage 
  

   through 
  the 
  water, 
  it 
  exercises 
  such 
  a 
  downward 
  pressure 
  on 
  the 
  rod 
  that 
  

   the 
  stopcocks 
  are 
  closed. 
  Arrived 
  at 
  the 
  surface, 
  it 
  contains 
  the 
  water 
  

   which 
  it 
  had 
  enclosed 
  at 
  the 
  depth 
  in 
  question. 
  A 
  small 
  safety-valve 
  

   allows 
  of 
  the 
  escape 
  of 
  the 
  surplus 
  water, 
  which, 
  owing 
  to 
  the 
  greater 
  

   density 
  of 
  the 
  water 
  below 
  the 
  surface, 
  it 
  has 
  enclosed 
  in 
  excess 
  of 
  what 
  

   it 
  can 
  hold 
  at 
  atmospheric 
  temperature 
  and 
  pressure. 
  The 
  apertures 
  of 
  

   the 
  stopcocks 
  being 
  necessarily 
  smaller 
  than 
  the 
  diameter 
  of 
  the 
  cylinder, 
  

   the 
  efficiency 
  of 
  the 
  instrument 
  in 
  really 
  changing 
  the 
  water 
  as 
  it 
  descends 
  

   was 
  tested 
  before 
  leaving 
  England 
  in 
  a 
  freshwater 
  lake, 
  the 
  water 
  with 
  

   which 
  it 
  was 
  filled 
  at 
  the 
  surface 
  containing 
  some 
  yellow 
  prussiate 
  of 
  

   potash. 
  It 
  was 
  found 
  that 
  the 
  water 
  fetched, 
  under 
  these 
  circum- 
  

   stances, 
  from 
  depths 
  over 
  \\ 
  fathom 
  was 
  unacted 
  upon 
  by 
  solution 
  of 
  

   perchloride 
  of 
  iron. 
  The 
  rate, 
  therefore, 
  of 
  change 
  of 
  water 
  is 
  satis- 
  

   factory, 
  as 
  we 
  can 
  be 
  certain 
  of 
  obtaining 
  an 
  average 
  sample 
  of, 
  at 
  the 
  

   most, 
  the 
  last 
  2 
  fathoms 
  passed 
  through 
  by 
  the 
  instrument. 
  

  

  The 
  variations 
  in 
  the 
  specific 
  gravity 
  of 
  the 
  water 
  which 
  forms 
  the 
  

   ocean 
  are, 
  comparatively 
  speaking, 
  so 
  slight, 
  that 
  an 
  instrument 
  of 
  con- 
  

  

  