On the Gulf Stream and contiguous currents. 353 



rent, that the great mechanical system of oceanic circulation is ap- 

 parently maintained, and which, with the operation of like causes 

 in the atmosphere, may be supposed to have a powerful influence 

 upon the climate of western Europe. Were the influence of winds 

 wholly unfelt upon the ocean, it is probable that the same system 

 would continue to be maintained, in all its essential features, by the 

 mechanical influences of the earth's rotation combined with an unsta- 

 ble state of equilibrium. The energy of this rotative influence, by 

 which the earth is flattened about twenty seven miles in its polar 

 diameter, and the depressive force of which, in each polar basin, is 

 equal to that of a column of mercury more than five ti:ousand feet in 

 height, is at least sufficient to maintain tlie existing movements and 

 mechanical relations of the terrestrial fluids, under the various and 

 continued oscillations to which these fluids are necessarily subjected. 



One fact, too important to be omitted here, will serve to demon- 

 strate the course and identity of the great ice-current for more than 

 half the distance from Cape Race in Newfoundland to the coast of 

 Massachusetts. On the 7th of July, 1836, H. M. packet Express 

 passed between two large ice islands to the southward of Nova Sco- 

 tia, in lat. 43<^ 13' N. Ion. 61° 17' W., temperature of the water 42 

 degrees, depth 45 fathoms ; the most western of these icebergs being 

 in lat. 43° 09', Ion. 61° 26', or about 75 miles southwesterly from 

 Sable Island. 



From the temperature of the sea upon the North American banks 

 and soundings, and in some other positions which are deemed anal- 

 ogous, it has been assumed that the mean temperature of the sea is 

 lower on shoals than in deep water, but it seems diflJicult to account 

 for such a result, unless upon the ground already mentioned. It 

 has, indeed, been ascribed to radiation from the bottom ; and again, 

 it has been denied that radiation from a non-luminous body can be 

 carried on freely through the water, and as the colder particles have 

 no tendency to rise towards the surface, it does not appear how the 

 supposed reduction in the temperature of the bottom can materially 

 affect a current of fifty or twenty fathoms in depth, which is derived 

 from a foreign source ; for on none of these shoals or soundings, is 

 the water permanently quiescent. Were it otherwise, we might rea- 

 sonably expect a diminution of temperature on shoals in winter, and 

 an increase in summer, with a pef manent increase, if in tropical lati- 

 tudes. I am informed by George W. Blunt, Esq., who has made a 

 course of regular thermometrical observations while crossing the At- 



Vol. XXXII.— No. 2. 45 



