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  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1929 
  

  

  assumed 
  that 
  the 
  two 
  axes 
  coincide; 
  but 
  this 
  is 
  by 
  no 
  means 
  certain, 
  

   and 
  only 
  systematic 
  observations 
  over 
  a 
  considerable 
  period 
  can 
  solve 
  

   this 
  problem. 
  

  

  LATERAL 
  BOUNDARIES 
  

  

  Within 
  the 
  straits 
  the 
  lateral 
  boundaries 
  of 
  the 
  Gulf 
  Stream 
  can 
  

   be 
  fixed 
  with 
  considerable 
  precision. 
  But 
  when 
  the 
  stream 
  issues 
  into 
  

   the 
  sea, 
  how 
  are 
  these 
  boundaries 
  to 
  be 
  determined? 
  On 
  the 
  west- 
  

   ern 
  side, 
  to 
  be 
  sure, 
  it 
  is 
  not 
  difficult 
  to 
  define 
  limits, 
  since 
  the 
  waters 
  

   of 
  the 
  stream 
  differ 
  in 
  color, 
  temperature, 
  salinity, 
  and 
  flow 
  from 
  

   the 
  inshore 
  coastal 
  waters. 
  But 
  on 
  the 
  east 
  the 
  Antilles 
  Current 
  

   comes 
  to 
  reinforce 
  the 
  Gulf 
  Stream, 
  so 
  that 
  its 
  waters 
  here 
  merge 
  

   gradually 
  with 
  the 
  waters 
  of 
  the 
  open 
  Atlantic. 
  In 
  terms 
  of 
  color, 
  

   temperature, 
  and 
  salinity 
  it 
  would 
  be 
  difficult 
  to 
  define 
  the 
  eastern 
  

   limits 
  of 
  the 
  Gulf 
  Stream. 
  With 
  regard 
  to 
  direction 
  of 
  flow, 
  however, 
  

   we 
  may 
  fix 
  the 
  limits 
  to 
  include 
  aU 
  the 
  water 
  flowing 
  parallel 
  to 
  the 
  

   axis. 
  These 
  limits 
  vary 
  with 
  the 
  seasons 
  and 
  with 
  changing 
  condi- 
  

   tions 
  of 
  wind 
  and 
  weather. 
  Furthermore, 
  our 
  knowledge 
  of 
  currents 
  

   in 
  the 
  open 
  sea 
  is 
  not 
  yet 
  sufficient 
  to 
  enable 
  us 
  to 
  fix 
  such 
  limits 
  with 
  

   precision. 
  Nevertheless, 
  from 
  such 
  charts 
  of 
  the 
  currents 
  of 
  the 
  

   Atlantic 
  as 
  Schott's 
  ^^ 
  and 
  Meyer's 
  ^^ 
  we 
  may 
  arrive 
  at 
  some 
  approxi- 
  

   mately 
  accurate 
  estimate 
  of 
  the 
  lateral 
  extent 
  of 
  the 
  Gulf 
  Stream. 
  

  

  It 
  has 
  generally 
  been 
  taken 
  that 
  the 
  inner 
  edge 
  of 
  the 
  Gulf 
  Stream, 
  

   from 
  its 
  outfall 
  into 
  the 
  sea 
  to 
  Cape 
  Hatteras, 
  is 
  defined 
  by 
  the 
  100- 
  

   fathom 
  curve. 
  But 
  recent 
  observations 
  by 
  the 
  Coast 
  and 
  Geodetic 
  

   Survey 
  indicate 
  that 
  it 
  lies 
  closer 
  inshore. 
  Systematic 
  current 
  obser- 
  

   vations 
  made 
  on 
  board 
  Diamond 
  Shoals 
  Light 
  Vessel, 
  which 
  is 
  anchor- 
  

   ed 
  in 
  30 
  fathoms 
  of 
  water 
  off 
  the 
  coast 
  of 
  North 
  Carolina 
  about 
  14 
  

   miles 
  southeast 
  of 
  Cape 
  Hatteras, 
  give 
  an 
  average 
  surface 
  current 
  

   here 
  of 
  0.4 
  knot 
  setting 
  N. 
  58° 
  E., 
  which 
  proves 
  that 
  along 
  this 
  stretch 
  

   of 
  the 
  coast 
  the 
  inner 
  edge 
  of 
  the 
  Gulf 
  Stream 
  lies 
  nearer 
  the 
  20- 
  

   fathom 
  curve 
  than 
  the 
  100-fathom 
  curve. 
  Taking 
  the 
  inner 
  limit 
  

   of 
  the 
  Gulf 
  Stream 
  as 
  far 
  as 
  Cape 
  Hatteras 
  to 
  be 
  defined 
  by 
  the 
  

   50-f 
  athom 
  curve, 
  and 
  the 
  outer 
  edge 
  to 
  be 
  defined 
  by 
  a 
  line 
  along 
  which 
  

   the 
  current 
  is 
  still 
  approximately 
  parallel 
  to 
  the 
  axis 
  of 
  the 
  Gulf 
  

   Stream, 
  the 
  width 
  of 
  the 
  stream 
  northward 
  of 
  its 
  outfall 
  is 
  as 
  follows: 
  

   Off 
  Cape 
  Canaveral, 
  about 
  70 
  miles; 
  off 
  the 
  coast 
  of 
  Georgia 
  after 
  

   its 
  union 
  with 
  the 
  Antilles 
  Current, 
  about 
  150 
  miles; 
  off 
  Cape 
  Hat- 
  

   teras 
  about 
  200 
  miles. 
  

  

  CONFLICT 
  WITH 
  THE 
  LABRADOR 
  CURRENT 
  

  

  The 
  region 
  off 
  Cape 
  Hatteras 
  has 
  been 
  called 
  the 
  "delta" 
  of 
  the 
  

   Gulf 
  Stream, 
  for 
  here 
  the 
  widespreading 
  current 
  separates 
  into 
  a 
  

  

  " 
  Scbott, 
  op. 
  cit., 
  PI. 
  XV, 
  following 
  p. 
  144. 
  

  

  " 
  H. 
  H. 
  F. 
  Meyer: 
  Die 
  Oberflachenstromungen 
  des 
  Atlantischen 
  Ozeans 
  im 
  Februar, 
  Veroffentl.Inst. 
  

   fiir 
  Meereskunde, 
  No. 
  11, 
  Berlin, 
  1923. 
  

  

  