6 



ON THE CAUSES OF THE 



of the water, and it is positively asserted that they do not 

 produce the great and deep currents of the ocean. It is neces- 

 sary, therefore, that we should advert to the nature of the 

 action of the wind, on water over which it is passing, in order 

 that we may see the force of this assertion. The atmosphere 

 presses with a weight of 15 lbs. on each square inch of the 

 surface of the water, and when that atmosphere is in motion 

 as a wind it continues to press with the same weight, and by 

 its friction must tend to impel the water forward in the 

 direction in which the wind is blowing. The immediate 

 effect of this wind, as is well known, is to cause a slight 

 ripple on the surface of the water : and afterwards in a short 

 time and in proportion to the velocity of the wind, to produce 

 small or large waves. The waves when formed present a 

 rougher surface for the wind to act on, and they enable it 

 more effectually to force the water forward in a horizontal 

 direction. Now this force being continued for a long time, 

 and acting over a large extent of surface, is, it is contended, 

 capable of producing a great general result, in communicating 

 motion to the waters of the great oceans. 



It is known, too, that the gases which constitute the atmos- 

 phere, to a certain extent penetrate the body of any water on 

 which they rest; the atmosphere may therefore be con- 

 sidered not to press altogether on the surface of the water, 

 but to some extent on that portion of the gases which the 

 body of the water contains. Now, when the atmosphere over 

 the sea is put in motion and becomes a wind, it must have a 

 tendency to carry with it, not only all the air that is above 

 the surface of the water, but also that portion which has 

 penetrated the body of it, and that is below the surface. 

 How far tfeis circumstance may cause the wind more effec- 

 tually to carry with it the water over which it is passing may 

 not be known, but the tendency of a wind to produce such an 

 effect is sufficiently apparent. 



That wind such as has been described, acting on the 



