in  its  Effect  on  Cultivation.  21 
hunters  and  fur-dealers;  but  happily  her  shores  are  washed  by  a 
more  genial  sea. 
52.  The  water  of  the  South  Atlantic  has  a general  movement 
westward  to  the  Gulf  of  Mexico,  into  which  also  the  Guiana 
current  Hows.  Here  entangled  and  confined,  the  water  becomes 
heated  as  in  a cauldron  to  a temperature  4°  above  that  of  the 
sea  under  the  equator,  and  8°  above  the  Atlantic  in  the  same 
latitude.  The  overflowing  of  this  accumulation  of  warm  water 
gives  rise  to  the  Gulf-stream.  The  stream  is  first  perceptible  on 
the  north-west  of  Cuba,  where  it  flows  weakly  to  the  east;  but, 
owing  to  the  narrowness  of  the  straits  of  Florida,  it  rushes  with 
great  velocity  through  this  channel,  runs  north  and  north-east 
along  the  coast  of  the  United  States  to  Cape  Hatteras,  from  thence 
it  inclines  more  to  the  east,  brushes  the  southern  extremity  of  the 
banks  of  Newfoundland,  and  runs  eastward  across  the  Atlantic  to 
the  Azores. 
53.  The  high  temperature  of  the  Gulf-stream  in  all  parts  of  its 
course  is  one  of  its  striking  peculiarities.  It  leaves  the  Gulf  in 
summer  at  86° — near  Cape  Hatteras  the  thermometer  shows  81°, 
or  from  10°  to  12°  above  the  water  of  the  ocean  under  the  same 
parallel,  hence  to  43°  of  longitude  the  thermometer  falls  to  75^°, 
and  at  the  Azores  to  7 2|°;  still  preserving  a temperature  of  from 
8°  to  10°  above  that  of  the  ocean. 
The  Gulf-stream,  and  its  widely-extended  overflowing,  form  a 
body  of  warm  water  of  great  extent  in  the  middle  of  the  Atlantic. 
Its  length  from  west  to  east  exceeds  2000  miles,  and  its  breadth 
may  be  taken  at  a mean  of  360  miles ; this  gives  an  area  equal  to 
four  times  the  extent  of  France,  and  larger  than  the  Mediterra- 
nean Sea.  The  prevailing  south-west  wind  has  its  origin  in  this 
part  of  the  Atlantic ; its  peculiar  mildness  and  humidity  being 
derived  from  the  warm  current  over  which  it  sweeps. 
54.  Thus  far  the  acknowledged  course  and  character  of  the 
Gulf-stream  have  been  described ; I shall  further  show  that  a 
large  portion  of  this  accumulation  of  warm  water  continues  to 
flow  in  a north-east  direction  along  the  western  shores  of  these 
Isles  and  the  coast  of  Norway. 
Major  Rennell  has  established  the  existence  of  a current,  which 
flows  east  from  the  Atlantic  along  the  north  coast  of  Spain,  and 
by  the  shores  of  the  Bay  of  Biscay  to  the  Scilly  Islands  and  St. 
George’s  Channel.  Dr.  Franklin  found  the  temperature  of  the 
Bay  of  Biscay  in  November,  1776,  to  be  60°. 
An  arm  of  the  gulf  stream  leaves  it  in  lat.  45°,  long.  30  W., 
and  runs  in  a north-east  direction  towards  the  coasts  of  Europe, 
and  becomes  very  strong  during  a continuance  of  south-west  wind. 
It  has  been  marked  on  some  charts  as  a “drift  current,”  though 
it  more  properly  forms  a necessary  part  of  a system  of  continuous 
