638 
ME. J. PRESTWICH ON SUBMARINE TEMPERATURES. 
irrespective of the surface isothermals, it must have an origin dependent not on local 
influences, but on others at a distance — such, in fact, as accord only with polar influences. 
b. That in the North Atlantic the two channels through which the deep-seated 
cold polar waters pass southward are Baffin Bay and the sea near the east coast of 
Greenland; while the shallower seas immediately west of Spitzbergen, and between 
that island and Norway, are occupied to their entire depth by warmer waters flowing 
northward, from equatorial regions, towards the pole. 
2. That in the North Atlantic the isotherm of 36° extends further in the polar seas 
than in the South Atlantic ; but in both its rise is masked by the extreme climatal 
variations and by surface-currents. 
3. — a. That in the equatorial regions of the Atlantic the deep-seated north and south 
polar waters, either owing to their meeting, or from impinging against projecting 
continental coasts, or from irregularities in the sea-hed, or from the several causes 
combined, are deflected and surge up at the surface, as shown by the rise of the bathy- 
metrical isotherms. 
• b. That the main portions of the upper strata of these surging waters flow slowly 
en masse from this equatorial zone towards the poles — such bodies of water moving 
independently of the drifts and surface-currents by which they are traversed and chan- 
nelled. 
4. — a. That in the Pacific there is a similar deep stratum of cold water at and under 
35°, extending from the Antarctic Ocean to Behring Sea without rising, as in the 
Atlantic, at the equator. 
b. That in the North Pacific the submarine temperature is as low as or lower than 
in the open North Atlantic in the same latitudes. 
c. Consequently, as the body of cold water in the North Pacific cannot be of north 
polar origin (comparatively none passing through Behring Strait), there is reason to 
believe that the south polar waters traverse the whole length of the Pacific, and rise 
against the coasts bounding that ocean on the north. 
5. That in the same way the Southern and Indian Oceans are underlaid by the 
cold waters proceeding from the Antarctic seas, which surge upwards as they approach 
the Asiatic coast. 
6. That there the surging-up of polar waters in the great oceans, and of tropical 
waters in Arctic and Antarctic seas, is intimately connected with some of the great 
surface-currents which originate, or acquire additional force, in equatorial and polar 
seas, although the ultimate course of these currents may be influenced and determined 
by the action of the prevailing winds and by the movement of rotation of the earth. 
7. That the temperature at depths in inland seas is governed by local causes, and 
tends in each case to assimilate to (or as near as the physical properties of water will 
allow) that of the mean winter or sub-winter temperature of the place. 
