Drift Ice and Cutrents of the North Atlantic. 385 



less nearly to the new direction of the current on which it floats, 

 the deeply immersed ice masses, having probably their greatest 

 bulk immersed in the lower or deeper current, are thus resolved, 

 by a real conflict of impelling forces, into a still different course, 

 which conforms more or less nearly to that of the lower or sub- 

 aqueous stream, according to the respective areas exposed to the 

 action of the two currents, and their respective velocities. The 

 geographical course of the body of the Gulf Stream, according to 

 our best information, commonly touches the southern point of the 

 Grand Bank in latitude 43° N., but the overflow or outspreading 

 portion of the Stream often sweeps over the southern part of the 

 Bank, as a surface current, when unimpeded by the ice. When 

 the ice appears in great quantities it is probable that the Gulf 

 Stream current coming from the west, carries the ice more east- 

 wardly, from its previous southwesterly course. In thus yielding 

 to the joint influence of the two currents, the surface ice assumes a 

 new direction, towards the south or southeast. 



Grounded icebergs, when quite stationary, afford the best means 

 for observing the course of the common ice fields. The course 

 of the ice-drift, within the influence of the Gulf Stream, doubtless 

 varies at difl!erent times and localities, and must be greatly influ- 

 enced by the depth of the floating masses. For in the case of 

 icebergs or islands, particularly those which come down from the 

 Greenland seas and pass eastward of the Grand Bank, their great 

 depth subjects them to the continued impulsion of the lower or 

 arctic current after they arrive within the influence of the Gulf 

 Stream, the main part of the cold current passing beneath the 

 warmer one, by means of its deeper position as well as greater 

 specific gravity. 



This may be shown from the cases before recited, of immense 

 icebergs which have been impelled into the body of the Gulf 

 Stream, where, instead of being drifted off" to the eastward, in con- 

 formity with its course and with the like tendency of the pre- 

 vailing winds, some of these floating islands have been forced 

 across the body of the stream, and in some cases even far beyond 

 its ordinary limits, to a latitude lower than that of the southern 

 boundary of Virginia ; as shown in the two cases given by Capt. 

 Couthouy. The most eastward of these, in longitude 39°, and 

 south from the usual eastern limit of the Greenland icebergs that 

 arrive in the latitude of the Banks, was near seven degrees lower 



