24:2 Proceedings of the Royal Physical Society. 
of the post -tertiary epoch. That western breeze, as is well 
known, though it brings a superabundance of moisture to 
the districts exposed to its influence, does not bring " glacial 
cold." The south-western counties of England and Ireland 
are not colder than those on the eastern shore ; but, on the 
contrary, are much warmer. 
We therefore conclude that the air lying above the inter- 
tropical oceans, saturated though it be with moisture, when 
conveyed to the higher latitudes, produces an effect the 
same in kind, though less in degree, as that of the air 
which is heated by contact with the land. The currents 
which it forms, like those from the land, with which they 
intermingle, flow in their northward or southward courses 
without hindrance, and, in so far as we can judge, without 
change. They cannot, therefore, be regarded as having pro- 
duced the phenomena that constitute the peculiarities of the 
glacial epoch. 
III. The third of the natural agencies, by which the 
equatorial heat is distributed over the earth, is that of the 
surface water of the intertropical seas. 
Those parts of the torrid zone which are covered with the 
deep receive the same amount of solar heat as those that are 
occupied by the land. This heat, however, is not com- 
municated to the air that lies above them, in the same 
manner, and in the same proportion, as that which falls on 
the land is communicated to the air that covers it. Some of 
the heat falling on the ocean, like that which falls on the 
solid earth , is lost by radiation into space. There is also a 
portion communicated to the air, to which we have already 
referred ; but the larger portion is expended in warming the 
water at the surface. The water thus heated becomes ex- 
panded, and consequently lighter than that which occupies 
the depths below ; and, like the air in contact with the in- 
tertropical land, it flows northward and southward to the 
poles. 
The effects produced by these warm oceanic currents are 
familiarly known, though the laws which regulate them, 
and the courses which they follow, have not been fully inves- 
tigated. The Gulf- Stream, for instance, on the coast of 
