﻿THE 
  GULP 
  STREAM 
  MAEMER 
  301 
  

  

  North 
  Atlantic 
  is 
  not 
  only 
  evidenced 
  by 
  a 
  chart 
  of 
  the 
  currents 
  but 
  

   is 
  also 
  clearly 
  indicated 
  by 
  the 
  temperature 
  of 
  the 
  surface 
  waters. 
  

   In 
  Figure 
  7 
  the 
  isotherms 
  of 
  the 
  surface 
  vvaters 
  of 
  the 
  North 
  Atlantic 
  

   are 
  shown 
  for 
  each 
  five 
  degrees 
  Fahrenheit. 
  The 
  northerly 
  sweep 
  of 
  

   the 
  isotherms 
  in 
  the 
  eastern 
  North 
  Atlantic 
  points 
  clearly 
  to 
  the 
  

   existence 
  of 
  a 
  current 
  moving 
  easterly 
  and 
  northerly 
  across 
  this 
  

   oceanic 
  basin. 
  

  

  CAUSES 
  OF 
  THE 
  GULF 
  STREAM 
  

  

  Ocean 
  currents 
  may 
  arise 
  from 
  any 
  one 
  or 
  more 
  of 
  a 
  number 
  of 
  

   causes. 
  Some 
  of 
  these 
  causes 
  reside 
  within 
  the 
  sea 
  itself, 
  others 
  

   originate 
  without. 
  Differences 
  in 
  level 
  between 
  two 
  regions 
  of 
  an 
  

   ocean 
  basin, 
  brought 
  about 
  by 
  whatever 
  agencies, 
  will 
  result 
  in 
  a 
  

   surface 
  current 
  from 
  the 
  higher 
  to 
  the 
  lower 
  level. 
  Differences 
  in 
  

   density, 
  whether 
  arising 
  from 
  difference 
  in 
  temperature 
  or 
  in 
  salinity 
  

   or 
  both, 
  will 
  bring 
  about 
  a 
  subsurface 
  current 
  from 
  and 
  a 
  return 
  sur- 
  

   face 
  current 
  to 
  the 
  region 
  of 
  greater 
  density. 
  Differences 
  in 
  atmos- 
  

   pheric 
  pressure 
  between 
  two 
  regions 
  will, 
  in 
  the 
  same 
  way, 
  bring 
  in 
  

   their 
  train 
  a 
  subsurface 
  current 
  from 
  and 
  a 
  return 
  surface 
  current 
  

   to 
  the 
  region 
  of 
  greater 
  pressure. 
  And 
  in 
  the 
  wind 
  we 
  have 
  at 
  once 
  

   the 
  most 
  obvious 
  and 
  the 
  most 
  familiar 
  of 
  the 
  agencies 
  that 
  bring 
  

   about 
  ocean 
  currents. 
  

  

  In 
  a 
  current 
  traversing 
  so 
  long 
  a 
  course 
  as 
  that 
  of 
  the 
  Gulf 
  Stream 
  

   it 
  is 
  plain 
  that 
  all 
  the 
  agencies 
  enumerated 
  above 
  enter 
  as 
  factors. 
  

   Clearly, 
  too, 
  the 
  relative 
  importance 
  of 
  the 
  different 
  agencies 
  must 
  

   vary 
  in 
  different 
  parts 
  of 
  the 
  course. 
  But 
  various 
  problems 
  of 
  an 
  

   hydrodynamic 
  character 
  must 
  yet 
  be 
  solved 
  before 
  a 
  numerical 
  

   evaluation 
  of 
  the 
  relative 
  importance 
  of 
  the 
  agencies 
  concerned 
  in 
  the 
  

   movement 
  of 
  the 
  Gulf 
  Stream 
  is 
  possible. 
  

  

  A 
  century 
  and 
  a 
  half 
  ago 
  Franklin 
  thought 
  that 
  the 
  Gulf 
  Stream 
  

   "is 
  probably 
  generated 
  by 
  the 
  great 
  accumulation 
  of 
  water 
  on 
  the 
  

   eastern 
  coast 
  of 
  America 
  between 
  the 
  tropics, 
  by 
  the 
  trade 
  winds 
  

   which 
  constantly 
  blow 
  there." 
  And 
  in 
  the 
  trade 
  winds, 
  which 
  bring 
  

   about 
  a 
  westerly 
  flow 
  of 
  the 
  waters 
  in 
  the 
  equatorial 
  regions 
  of 
  the 
  

   Atlantic 
  Ocean, 
  is 
  still 
  found 
  the 
  primary 
  cause 
  of 
  the 
  Gulf 
  Stream. 
  

   As 
  appears 
  from 
  Figure 
  6, 
  the 
  vvaters 
  of 
  the 
  South 
  Equatorial 
  Current 
  

   are 
  the 
  first 
  to 
  strilvc 
  the 
  coast, 
  the 
  greater 
  part 
  being 
  directed 
  north- 
  

   westward 
  into 
  the 
  Caribbean 
  Sea 
  where 
  they 
  reinforce 
  the 
  flow 
  of 
  

   the 
  North 
  Equatorial 
  Current. 
  From 
  the 
  Caribbean 
  the 
  combined 
  

   flow 
  comes 
  into 
  the 
  Gulf 
  of 
  Mexico 
  whence 
  it 
  issues 
  as 
  the 
  Gulf 
  

   Stream 
  into 
  the 
  Straits 
  of 
  Florida. 
  

  

  Now 
  while 
  the 
  Gulf 
  Stream 
  is 
  traced 
  to 
  the 
  trade 
  winds, 
  the 
  stream 
  

   is 
  not 
  a 
  wind 
  or 
  drift 
  current 
  as 
  are 
  the 
  North 
  and 
  South 
  Equatorial 
  

   Currents. 
  The 
  accumulation 
  of 
  water 
  resulting 
  from 
  the 
  trade 
  winds 
  

   brings 
  about 
  a 
  gradient 
  current. 
  This 
  means 
  that 
  a 
  higher 
  level 
  of 
  

  

  