28 THE PHYSICAL GEOGRAPHY OF THE SEA. 



the Atlantic than when they arrive off the Banks of Newfound- 

 land ; for in consequence of the difference of latitude between the 

 parallels of these two places, their rate of motion around the axis 

 of the eartli is reduced from nine hundred and fifteen^* to seven 

 hundred and fifty-eight miles the hour. Hence this immense vol- 

 ume of water would, if we suppose it to pass from the Bahamas 

 to the Grand Banks in an hour, meet with an opposing force in 

 the shape of resistance sufficient, in the aggregate, to retard it two 

 miles and a half the minute in its eastwardly rate. If the actual 

 resistance be calculated according to received laws, it will be 

 found equal to several atmospheres. And by analogy, bow inad- 

 equate must the pressure of the gentle trade-winds be to such, re- 

 sistance, and to the effect assigned them ! 



92. If, therefore, in the proposed inquiry, we search, for a pro- 

 The Gulf stream can pelliug powcf uowhcrc but in the liigheT level of the 

 by a higher level. Gulf, or iu the "billiard-ball" rebound from its 

 shores, we must admit, in the head of water there, the existence 

 of a force capable of putting in motion, and of driving over a 

 plain at the rate of four miles the hour, all the waters, as fast as 

 they can be brought down by three thousand (§ 75) such streams 

 as the Mississippi Kiver — a power, at least, sufficient to overcome 

 the resistance required to reduce from two miles and a half to a 

 few feet per minute the velocity of a stream that keeps in perpet- 

 ual motion one fourth of all the waters in the Atlantic Ocean. 



93. The advocates of the trade-wind theory, whether, with 

 Nor by the trade- Fraukliu (§ 77), they make the propelling power to 

 wind theory. |^q dcrivcd from a " head of water'^ in the Gulf, or, 

 with Ilerschel (§ 79), from the rebound, a la billiard-balls, against 

 its shores, require that the impulse then and there communicated 

 to the waters of the Gulf Stream should be sufficient 4o send them 

 entirely across the Ocean ; for in neither case does their theory 

 provide for any renewal of the propelling power by the wayside. 

 Can this be ? Can water flow on any more than cannon balls can 

 continue their flight after the propelling force has been expended ? 



94. When we inject water into a pool, be the force never so 

 Illustration. great, the jet is soon overcome, broken up, and 



* Or, 915. 2G to 758. GO. On the latter parallel the current has an east set of about 

 one and a half miles the hour, making the true velocity to the east, and on the axis 

 of the earth, about seven hundred and sixty miles an hour at the Grand Banks. 



