﻿302 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  19 
  29 
  

  

  the 
  water 
  must 
  obtain 
  in 
  the 
  Gulf 
  of 
  Mexico 
  than 
  out 
  in 
  the 
  open 
  sea 
  

   north 
  of 
  the 
  Straits 
  of 
  Florida. 
  Agassiz 
  quotes 
  Hilgard 
  as 
  regarding 
  

   the 
  Gulf 
  of 
  Mexico 
  "as 
  an 
  immense 
  hydrostatic 
  reservoir 
  rising 
  to 
  

   the 
  height 
  of 
  more 
  than 
  3 
  feet 
  above 
  the 
  general 
  oceanic 
  level, 
  and 
  

   from 
  this 
  supply 
  comes 
  the 
  Gulf 
  Stream, 
  which 
  passes 
  out 
  through 
  

   the 
  Straits 
  * 
  * 
  * 
  the 
  only 
  opening 
  left 
  for 
  its 
  exit." 
  ^^ 
  And 
  in 
  a 
  

   footnote 
  he 
  adds, 
  "By 
  a 
  most 
  careful 
  series 
  of 
  levels, 
  run 
  from 
  Sandy 
  

   Hook 
  and 
  the 
  mouth 
  of 
  the 
  Mississippi 
  River 
  to 
  St. 
  Louis, 
  it 
  was 
  

   discovered 
  that 
  the 
  Atlantic 
  Ocean 
  at 
  the 
  first 
  point 
  is 
  40 
  inches 
  lower 
  

   than 
  the 
  Gulf 
  of 
  Mexico 
  at 
  the 
  mouth 
  of 
  the 
  Mississippi." 
  In 
  a 
  

   paper 
  published 
  in 
  1914 
  Hep 
  worth 
  states, 
  "As 
  regards 
  the 
  Gulf 
  

   Stream, 
  and 
  its 
  causation, 
  it 
  was 
  found 
  by 
  the 
  officers 
  of 
  the 
  United 
  

   States 
  Coast 
  Survey 
  that 
  the 
  Atlantic 
  Ocean 
  at 
  Sandy 
  Hook 
  was 
  3 
  

   to 
  4 
  feet 
  lower 
  than 
  the 
  waters 
  of 
  the 
  Gulf 
  of 
  Mexico 
  at 
  the 
  mouth 
  

   of 
  the 
  Mississippi." 
  ^° 
  

  

  It 
  should 
  be 
  remembered 
  that 
  leveling 
  of 
  even 
  the 
  highest 
  precision 
  

   is 
  subject 
  to 
  instrumental 
  errors 
  which, 
  while 
  very 
  small 
  for 
  moderate 
  

   distances, 
  may 
  become 
  relatively 
  large 
  between 
  widely 
  separated 
  

   points. 
  More 
  recent 
  results 
  reduce 
  very 
  much 
  the 
  difference 
  in 
  level 
  

   between 
  the 
  Gulf 
  of 
  Mexico 
  and 
  the 
  Atlantic 
  and 
  bring 
  to 
  light 
  the 
  

   fact 
  that 
  this 
  is 
  a 
  highly 
  involved 
  matter. 
  Avers 
  recently 
  studied 
  

   this 
  question 
  in 
  connection 
  with 
  the 
  broader 
  question 
  of 
  the 
  deviations 
  

   of 
  local 
  sea 
  level 
  from 
  a 
  level 
  surface.^^ 
  His 
  results, 
  which 
  are 
  based 
  

   on 
  the 
  best 
  available 
  data, 
  may 
  be 
  summarized 
  as 
  follows: 
  From 
  

   Galveston, 
  Texas, 
  to 
  Cedar 
  Keys, 
  on 
  the 
  west 
  coast 
  of 
  Florida, 
  the 
  

   level 
  of 
  the 
  Gulf 
  slopes 
  downward, 
  the 
  difference 
  between 
  the 
  two 
  

   places 
  being 
  0.43 
  foot. 
  The 
  level 
  of 
  the 
  Gulf 
  at 
  Cedar 
  Keys 
  is 
  0.36 
  

   foot 
  higher 
  than 
  the 
  level 
  of 
  the 
  Atlantic 
  Ocean 
  at 
  St. 
  Augustine 
  on 
  the 
  

   eastern 
  coast 
  of 
  Florida. 
  But 
  from 
  St. 
  Augustine 
  northward 
  there 
  is 
  

   an 
  upward 
  slope 
  of 
  sea 
  level 
  all 
  along 
  the 
  Atlantic 
  coast 
  of 
  the 
  United 
  

   States; 
  so 
  that 
  in 
  the 
  vicinity 
  of 
  Sandy 
  Hook 
  sea 
  level 
  is 
  actually 
  

   0.62 
  foot 
  higher 
  than 
  at 
  St. 
  Augustine 
  and 
  but 
  0.16 
  foot 
  below 
  the 
  

   Gulf 
  level 
  at 
  Galveston. 
  

  

  This 
  upward 
  slope 
  of 
  sea 
  level 
  along 
  the 
  Atlantic 
  coast 
  of 
  the 
  United 
  

   States 
  does 
  not 
  necessarily 
  mean 
  that 
  the 
  Gulf 
  Stream 
  is 
  moving 
  

   uphill. 
  For 
  the 
  main 
  body 
  of 
  the 
  Gulf 
  Stream 
  is 
  a 
  number 
  of 
  miles 
  off 
  

   the 
  coast, 
  and 
  there 
  may 
  well 
  be 
  a 
  downward 
  slope 
  of 
  sea 
  level 
  out- 
  

   ward 
  from 
  the 
  coast. 
  The 
  question 
  of 
  sea 
  level 
  itself 
  is 
  one 
  compli- 
  

   cated 
  by 
  many 
  factors, 
  and 
  the 
  exact 
  determination 
  of 
  the 
  difference 
  

   in 
  level 
  between 
  the 
  Gulf 
  and 
  the 
  open 
  sea 
  bristles 
  with 
  numerous 
  

   unsolved 
  problems. 
  

  

  '• 
  Alexander 
  Agassiz: 
  Three 
  Cruises 
  of 
  the 
  United 
  States 
  Coast 
  and 
  Geodetic 
  Survey 
  Steamer 
  "Blake" 
  

   Vol. 
  I, 
  p. 
  249, 
  Boston 
  and 
  New 
  Yorls, 
  1888. 
  

  

  20 
  M. 
  W. 
  Campbell 
  Hepworth: 
  The 
  Gulf 
  Stream, 
  Geogr. 
  Journ., 
  Vol. 
  44, 
  pp. 
  429-452 
  and 
  534-553, 
  1914; 
  

   reference 
  on 
  p. 
  435. 
  

  

  21 
  H. 
  G. 
  Avers: 
  A 
  study 
  of 
  the 
  Variation 
  of 
  Mean 
  Sea-Level 
  from 
  a 
  Level 
  Surface, 
  Bull. 
  Natl. 
  Research 
  

   Council, 
  No. 
  61 
  (=Trans. 
  Amer. 
  Geophys. 
  Union, 
  1927), 
  pp. 
  56-58, 
  Washington, 
  1927. 
  

  

  