832 OYSTERS, AND ALL ABOUT THEM. 



Gladly would I avail myself of the opportunity of 

 quoting further from this interesting and highly instructive 

 book, but that the tempting pursuit were of too digressive 

 a nature for the subject in view. But those who read his 

 work cannot do otherwise than follow the writer into all 

 the ingenious proofs adduced in support of his views, and 

 agree with him that the grand currents of the ocean are 

 occasioned by the endless variations in temperature, specific 

 gravity, and saltness of its waters, as well as a multitude of 

 other agencies which extend from the poles to the equator ; 

 and that, of those causes, the winds represent merely a 

 unit, and act solely on the surface of the sea, or to the 

 extent of a few fathoms below it. The rain and the snow 

 which fall upon its surface serve equally to disturb the 

 3quilibrium, as well as evaporation in one quarter, conge- 

 lation in another ; and although the sea has its deserts as 

 well as the land, yet its waters are far more densely filled 

 with animal and vegetable life than either the air or terra 

 firma ; and every creature, every coral, every phosphores- 

 cent molecule and weed, is ever abstracting or adding to 

 the component parts of the waters in which they exist ; 

 their action is as ceaseless as the variations of heat and 

 cold which cause our atmosphere to be ever in motion, 

 thus calling for perpetual oceanic currents to undo their 

 perpetual work. 



To give the reader an idea how very particularly and 

 how thoroughly the coast survey was accomplished by 

 Lieut. Winslow, I will give an example of one particular 

 part of his work which may serve as a guide as to what can 

 and perhaps ought to be done elsewhere. 



It is but fair to him to add that I have very much 

 condensed his Report, which, being rather copious, might 

 not, upon that account, serve to interest readers on this 



