50 
THE PHYSICAL GEOGRAPHY OF THE SEA. 
ference in surface temperature as an index of the heat accumu- 
lated there, a simple calculation will show that the quantity of 
specific heat daily carried off by the Gulf Stream from those re- 
gions, and discharged over the Atlantic, is sufficient to raise mount- 
ains of iron from zero to the melting point, and to keep in flow^ 
from them a molten stream of metal greater in volume than the 
waters daily discharged from the Mississippi River. Who^ there- 
fore, can calculate the benign influence of this wonderful current 
upon the climate of the South ? In the pursuit of this subject, 
the mind is led from nature up to the Great Architect of nature : 
and what mind will the study of this subject not fill with profita- 
ble emotions ? Unchanged and unchanging alone, of all created 
things, the ocean is the great emblem of its everlasting Creator. 
" He treadeth upon the waves of the sea," and is seen in the won- 
ders of the deep. Yea, " He calleth for its waters, and poureth 
them out upon the face of the earth." 
In obedience to this call, the aqueous portion of our planet pre- 
serves its beautiful system of circulation. By it heat and warmth 
are dispensed to the extra-tropical regions ; clouds and rain are 
sent to refresh the dry land ; and by it coohng streams are brought 
from Polar Seas to temper the heat of the torrid zone. At the 
depth of two hundred and forty fathoms, the temperature of the 
currents setting into the Caribbean Sea has been found as low as 
48°, while that of the surface was 85°. Another cast with three 
hundred and eighty-six fathoms gave 43° below against 83° at the 
surface. The hurricanes of those regions agitate the sea to great 
depths ; that of 1780 tore rocks up from the bottom in seven 
fathoms, and cast them on shore. They therefore can not fail to 
bring to the surface portions of the cooler water below. 
At the very bottom of the Gulf Stream, when its surface tem- 
perature was 80°, the deep sea thermometer of the Coast Survey 
has recorded temperatures as low as 38° Fahrenheit. 
These cold waters doubtless come down from the north to re- 
place the warm water sent through the Gulf Stream to moderate 
the cold of Spitzbergen ; for within the Arctic Circle, the temper- 
ature at corresponding depths off" the shores of that island is only 
one degree colder than in the Caribbean Sea, while on the coasts 
of Labrador the temperature in depth is said to be 25°, or 7° be- 
Jow the melting point of fresh water. Captain Scoresby relates, 
