THE GULF STREAM. 43 



transfernng deposits from the north for these shoals, and of snow- 

 ing down upon them the infusoria and the corpses of "livino' 

 creatures" that are spawned so abundantly in the warm waters of 

 the Gulf Stream, and sloughed off in myriads for burial where the 

 conflict between it and the great Polar current (§ 14) takes place, 

 is everlastingly going on. These agencies, with time, seem alto- 

 gether adequate to the formation of extensive bars or banks. 



The deep sea soundings that have been made by vessels of the 

 navy (Plate XL) tend to confirm this view as to the formation of 

 these Banks. The greatest contrast in the bottom of the Atlantic 

 is just to the south of these Banks. Nowhere in the open sea has 

 the water been found to deepen so suddenly as here. Coming 

 from the north, the bottom of the sea is shelving ; but suddenly, 

 after passing these Banks, its depth increases by almost a precip- 

 itous descent for many thousand feet, thus indicating that the de- 

 bris which forms the Grand Banks comes from the north. 



47. From the Straits of Bemini the course of the Gulf Stream 

 (Plate YI.) describes (as far as it can be traced over toward the 

 British Islands which are in the midst of its waters) the arc of a 

 great circle as nearly as may be. Such a course as the Gulf 

 Stream takes is very nearly the course that a cannon ball, could 

 it be shot from these straits to those islands, would describe. 



If it were possible to see Ireland from Bemini, and to get a can- 

 non that would reach that far, the person standing on Bemini and 

 taking aim, intending to shoot at Ireland as a target, would, if the 

 earth were at rest, sight direct, and make no allowance for differ- 

 ence of motion between marksman and target. 



48. But there is diurnal rotation ; the earth does revolve on its 

 axis ; and since Bemini is nearer to the equator than Ireland is, 

 the gun would be moving in diurnal rotation (§ 16) faster than the 

 target, and therefore the marksman, taking aim point blank at his 

 target, would miss. He would find, on examination, that he had 

 shot south — that is, to the right (§ 43) of his mark. In other 

 words, that the path actually described by the ball would be the 

 resultant of this difference in the rate of rotation and the traject- 

 ile force ; the former, impelling to the east, would cause the ball 

 to describe a great circle, but one witli too much obliquity to pass 



