Theory of Marine Currents. 161 
cause analogous to that of the trade-winds and their counter- 
currents, while he, at the same time, has pointed out the in- 
fluence of these winds on the current of the northern basin 
of the Atlantic. It will afterwards be soon enough to trace 
the history of it, when the theory of marine currents shall be. 
generally known and adopted. 
Let us consider an oceanic basin, such as the northern 
part of the Atlantic, comprised between the equator on the 
south, the polar circle on the north, the Old and New World 
on the east and west; it is evident that, in this vast liquid 
plain, the tropical part, dilated by the heat, would be thereby 
elevated, and form a layer whose upper portion would exceed 
the level of more northern seas, and would tend to direct it- 
self towards the waters of the north; while, at the same 
time, the latter, in consequence of the excess of pressure re- 
sulting from the new superincumbent mass, and from the 
deficiency produced by this same transportation in the pres- 
sure of the tropical columns, would tend to flow southwards 
in an under current, so that if the earth had no rotatory mo- 
tion, we would observe, on the one hand, a kind of current 
or cascade from south to north throughout the whole breadth 
of the Atlantic, which south-north and superior flow of waters 
would be compensated by a similar one below, but running 
from north to south. An analogous effect would be produced 
in the four other similar basins which physical geography 
presents us with, namely. the southern part of the Atlantic, 
the northern part of the Pacific, the southern part of the 
same ocean, and, lastly, the Indian Sea, bounded on the 
north by Asia, on the west by Africa, on the east by the 
Islands of Sunda and New Holland, and on the south by the 
Antarctic Ocean. To complete the division of the terrestrial 
waters, we may add to these five great basins two circular 
basins, the one between the icy regions of the South Pole and 
the southern limits of the current of the Indian Sea, the cur- 
rent of the Pacific, and that of the Atlantic ; the other, be- 
tween the arctic ice and the northern limits of the Old and 
New Continent. 
Let us return to our five great basins, of which the two 
northern ones carry their warm superficial waters to the 
VOL. XLVI. NO. xCV.—JAN. 1850. L 
