Chap. XVII.] THE WINDS AND EVAPORATION. 181 



tliis, as I have above stated, is the very point at 

 issue. 



Captain Manry, whose experience in this matter, 

 both practical and theoretical, is unrivalled, clearly 

 recognises that the winds indisputably do tend to 

 cause currents ; but considers that, in respect to 

 other current- creating forces, their action is com- 

 paratively trivial, and altogether insufficient to 

 account for the currents which actually exist in the 

 ocean. 



Sir John Herschel is surprised that Captain 

 Maury can see ' any possible ground for doubting 

 that the Gulf Stream owes its origin entirely to the 

 Trade Winds ' : and considers that ' if there were no 

 atmosphere there would be no Gulf Stream, or any 

 other considerable oceanic current (as distinguished 

 from a mere surface drift) whatever.' ^ In reply to 

 this alleged supremacy of the winds among current- 

 creating forces, Captain Maury says : — ' We know of 

 mstances in which waters have been accumulated on 

 one side of a lake, or in one end of a canal, at the 

 expense of the other. The pressure of the Trade 

 Winds may assist to give the Gulf Stream its initial 

 velocity, but are they themselves adequate to such 

 an effect ? Exammation shows that they are not. 

 AVith the view of ascertaining the average number 

 of days durmg the year that the NE. Trade Winds 



^ Encyclopcedia Britannica : Article, Physical Geography, 

 sec. 57. 



