﻿1874.] 
  Distribution 
  of 
  Temperature 
  in 
  the 
  Ocean. 
  

  

  125 
  

  

  observed) 
  the 
  slightly 
  concentrated 
  water 
  descending 
  from 
  the 
  surface 
  as 
  

   the 
  winter 
  approaches 
  does 
  not 
  meet 
  water 
  of 
  greater 
  density 
  at 
  the 
  same 
  

   temperature 
  than 
  its 
  own. 
  Unfortunately 
  the 
  determination 
  of 
  the 
  

   specific 
  gravity 
  of 
  water 
  below 
  the 
  surface 
  is 
  much 
  less 
  simple 
  than 
  that 
  

   of 
  the 
  temperature 
  ; 
  for 
  although 
  we 
  have 
  an 
  instrument 
  which 
  gives, 
  

   within 
  any 
  required 
  degree 
  of 
  accuracy, 
  the 
  density 
  of 
  the 
  water 
  at 
  any 
  

   depth 
  in 
  exactly 
  the 
  same 
  way 
  as 
  the 
  thermometer 
  gives 
  its 
  tempera- 
  

   ture, 
  the 
  results 
  of 
  the 
  observations 
  are 
  composed 
  of 
  three 
  factors, 
  which 
  

   depend 
  on 
  the 
  temperature, 
  the 
  pressure, 
  and 
  the 
  salinity. 
  By 
  sending 
  

   down 
  a 
  thermometer 
  along 
  with 
  it 
  we 
  might 
  clear 
  the 
  result 
  for 
  tem- 
  

   perature 
  ; 
  by 
  noting 
  the 
  depth 
  we 
  might 
  clear 
  for 
  pressure 
  ; 
  but 
  the 
  result 
  

   so 
  cleared 
  would 
  not 
  represent 
  the 
  salinity 
  of 
  the 
  water 
  at 
  the 
  depth 
  in 
  

   question, 
  but 
  the 
  average 
  excess 
  of 
  salinity 
  of 
  the 
  column 
  of 
  water 
  above 
  

   it, 
  over 
  or 
  under 
  the 
  mean 
  salinity 
  assumed 
  for 
  sea-water 
  in 
  the 
  calcula- 
  

   tion 
  of 
  the 
  pressure 
  exercised 
  by 
  a 
  column 
  of 
  it. 
  There 
  remains, 
  there- 
  

   fore, 
  nothing 
  for 
  it 
  but 
  to 
  fetch 
  a 
  sample 
  of 
  water 
  from 
  each 
  depth, 
  and 
  

   determine 
  its 
  specific 
  gravity 
  on 
  board. 
  As 
  this 
  is 
  an 
  operation 
  which 
  

   takes 
  up 
  some 
  time, 
  the 
  number 
  of 
  " 
  serial 
  specific-gravity 
  " 
  determina- 
  

   tions 
  is 
  comparatively 
  small. 
  

  

  The 
  following 
  are 
  the 
  results 
  of 
  two 
  which 
  were 
  obtained 
  on 
  the 
  

   voyage 
  between 
  Bermuda 
  and 
  the 
  Azores. 
  The 
  results 
  show 
  the 
  specific 
  

   gravity 
  at 
  60° 
  F., 
  that 
  of 
  water 
  at 
  39 
  p 
  -2 
  F. 
  being 
  taken 
  as 
  unity. 
  

  

  I. 
  was 
  taken 
  on 
  the 
  18th 
  June, 
  1873, 
  in 
  lat. 
  35° 
  7' 
  N., 
  long. 
  52° 
  32' 
  W. 
  

  

  II. 
  was 
  taken 
  on 
  the 
  24th 
  June, 
  1873, 
  in 
  lat. 
  38° 
  3' 
  N., 
  long. 
  

   39° 
  19' 
  W. 
  

  

  For 
  comparison 
  I 
  give 
  one 
  equatorial 
  and 
  one 
  South- 
  Atlantic 
  " 
  serial 
  

   specific-gravity 
  " 
  determination. 
  

  

  III. 
  was 
  taken 
  on 
  the 
  21st 
  August, 
  1873, 
  in 
  lat. 
  3° 
  8' 
  N., 
  long. 
  

   14° 
  49' 
  W. 
  

  

  IV. 
  was 
  taken 
  on 
  the 
  3rd 
  October, 
  1873, 
  in 
  lat. 
  26° 
  15' 
  S., 
  long. 
  

   32° 
  56' 
  W. 
  

  

  

  

  Specific 
  gravity 
  at 
  60° 
  F. 
  

  

  

  Depth 
  

  

  Distilled 
  water 
  at 
  39°-2=l. 
  

  

  in 
  fathoms. 
  

  

  

  

  

  

  I. 
  

  

  II. 
  

  

  III. 
  

  

  IV. 
  

  

  

  

  1-02712 
  

  

  1-02684 
  

  

  1-02591 
  

  

  1-02703 
  

  

  50 
  . 
  

  

  

  

  1-02658 
  

  

  1-02682 
  

  

  100 
  

  

  

  

  1-02643 
  

  

  1-02649 
  

  

  150 
  

  

  1-02701 
  

  

  1-02677 
  

  

  

  

  200 
  

  

  

  

  1-02620 
  

  

  1-02608 
  

  

  250 
  

  

  1-02683 
  

  

  1-02641 
  

  

  

  

  300 
  

  

  

  

  1-02610 
  

  

  1-02573 
  

  

  400 
  

  

  

  

  1-02629 
  

  

  1-02554 
  

  

  500 
  

  

  1-0*2604 
  

  

  1-02608 
  

  

  

  

  VOL. 
  XXIII. 
  L 
  

  

  