kind needed. It is a landlocked sea which runs nearly east and west,
between the twenty-ninth and forty-fifth parallels of north latitude.
Roughly speaking, the average temperature of the air over it is 75° Fahr.
in July and 48° in January.

This great expanse of water is divided by the peninsula of Italy
(including Sicily), continuous with which is a submarine elevation
carrying less than 1,200 feet of water, which extends from Sicily to Cape
Bon in Africa, into two great pools--an eastern and a western. The
eastern pool rapidly deepens to more than 12,000 feet, and sends off to
the north its comparatively shallow branches, the Adriatic and the Aegean
Seas. The western pool is less deep, though it reaches some 10,000 feet.
And, just as the western end of the eastern pool communicates by a
shallow passage, not a sixth of its greatest depth, with the western
pool, so the western pool is separated from the Atlantic by a ridge which
runs between Capes Trafalgar and Spartel, on which there is hardly 1,000
feet of water. All the water of the Mediterranean which lies deeper than
about 150 fathoms, therefore, is shut off from that of the Atlantic, and
there is no communication between the cold layer of the Atlantic (below
1,000 fathoms) and the Mediterranean. Under these circumstances, what is
the temperature of the Mediterranean? Everywhere below 600 feet it is
about 55° Fahr.; and consequently, at its greatest depths, it is some 20°
warmer than the corresponding depths of the Atlantic.

It seems extremely difficult to account for this difference in any other
way, than by adopting the views so strongly and ably advocated by Dr.
Carpenter, that, in the existing distribution of land and water, such a
circulation of the water of the ocean does actually occur, as
theoretically must occur, in the universal ocean, with which we started.