﻿ACADEMY 
  OF 
  SCIENCES. 
  343 
  

  

  Professor 
  Davidson 
  communicated 
  to 
  the 
  Academy 
  the 
  general 
  

   results 
  of 
  the 
  recent 
  survey 
  made 
  by 
  Commander 
  Belknap, 
  of 
  the 
  

   United 
  States 
  steamer 
  Tuscarora, 
  on 
  the 
  proposed 
  southern 
  route 
  

   for 
  the 
  telegraph 
  cable 
  from 
  this 
  coast 
  to 
  Japan 
  ; 
  his 
  remarks 
  were 
  

   illustrated 
  with 
  charts 
  and 
  drawings. 
  In 
  the 
  soundings 
  from 
  San 
  

   Francisco 
  to 
  San 
  Diego, 
  a 
  great 
  many 
  off-shore 
  lines 
  were 
  run. 
  

   Ninety 
  miles 
  off 
  Point 
  San 
  Luis 
  the 
  depth 
  increased 
  to 
  2,000 
  

   fathoms, 
  with 
  gray 
  greenish 
  ooze 
  at 
  the 
  bottom, 
  aud 
  a 
  temperature 
  

   of 
  a 
  little 
  over 
  82 
  degrees. 
  Off 
  Cape 
  Mendocino 
  a 
  plateau 
  was 
  

   found, 
  with 
  a 
  depth 
  of 
  2,500 
  fathoms. 
  Off 
  San 
  Nicolas, 
  at 
  the 
  

   distance 
  of 
  33 
  or 
  3-1 
  miles, 
  the 
  depth 
  was 
  2,000 
  fathoms. 
  Down 
  

   the 
  California 
  coast 
  the 
  ooze 
  became 
  greenish, 
  until 
  San 
  Diego 
  was 
  

   approached, 
  and 
  on 
  the 
  plateau 
  off 
  there 
  a 
  greenish 
  yellowish 
  

   ooze 
  was 
  obtained. 
  Thence 
  across 
  to 
  Honolulu 
  the 
  ooze 
  was 
  yel- 
  

   lowish, 
  then 
  yellowish 
  brown, 
  and 
  finally 
  brown 
  near 
  Honolulu. 
  

   In 
  all 
  cases 
  the 
  signs 
  of 
  former 
  life 
  brought 
  up 
  were 
  the 
  same 
  as 
  

   those 
  obtained 
  on 
  the 
  Northern 
  Pacific 
  Coast. 
  

  

  To 
  Honolulu 
  the 
  distance 
  is 
  2,200 
  miles. 
  The 
  bottom 
  averages 
  

   2,565 
  fathoms 
  in 
  depth, 
  or 
  15,510 
  feet, 
  and 
  the 
  average 
  tempera- 
  

   ture 
  is 
  33 
  6-10 
  deg. 
  Much 
  more 
  than 
  one-half 
  of 
  this 
  water 
  along 
  

   the 
  ocean-bed 
  has 
  a 
  temperature 
  of 
  35 
  degs. 
  only 
  ; 
  above 
  this 
  came 
  

   a 
  stratum 
  of 
  water 
  heated 
  to 
  40 
  deg., 
  and 
  above 
  this 
  again, 
  water 
  

   heated 
  to 
  50 
  deg. 
  Upon 
  a 
  calculation 
  of 
  the 
  volume 
  of 
  water 
  be- 
  

   tween 
  this 
  coast 
  and 
  Honolulu, 
  along 
  the 
  line 
  of 
  soundings, 
  he 
  

   estimated 
  the 
  quantity 
  at 
  1,858,000 
  cubic 
  miles. 
  Of 
  this, 
  1,046,- 
  

   000 
  cubic 
  miles 
  range 
  in 
  temperature 
  from 
  33.6 
  to 
  35. 
  Between 
  

   the 
  temperature 
  of 
  35 
  and 
  40 
  there 
  are 
  582,000 
  cubic 
  miles 
  ; 
  from 
  

   40 
  to 
  50 
  degs., 
  180,000 
  cubic 
  miles 
  ; 
  and 
  from 
  50 
  degs. 
  to 
  the 
  

   highest 
  temperature, 
  which 
  is 
  found 
  over 
  at 
  Honolulu, 
  73J 
  degs., 
  

   the 
  volume 
  is 
  100,000 
  cubic 
  miles. 
  In 
  other 
  words, 
  the 
  film 
  of 
  

   surface-water 
  ranging 
  from 
  59 
  to 
  73 
  6-10 
  is 
  only 
  one-tenth 
  of 
  the 
  

   mass 
  of 
  water 
  below 
  it. 
  Apparently, 
  the 
  grade 
  is 
  very 
  steep 
  at 
  

   Honolulu 
  and 
  off 
  San 
  Diego, 
  but 
  in 
  reality 
  it 
  never 
  exceeds 
  one 
  

   foot 
  in 
  twenty-six 
  ; 
  no 
  greater 
  impediment 
  to 
  cable-laying 
  is 
  en- 
  

   countered 
  from 
  Honolulu 
  to 
  Bonin 
  Island, 
  where 
  there 
  is 
  the 
  great- 
  

   est 
  depth 
  of 
  the 
  route, 
  3,262 
  fathoms, 
  nor 
  thence 
  to 
  Japan. 
  In 
  

   sounding 
  to 
  Bonin 
  several 
  submarine 
  mountains 
  were 
  discovered, 
  

  

  