TKADE-WINDS OF THE SOUTHERN HEMISPHERE. 351 



1003. The circumstances and considerations wluch seemed to 

 be in favor of this conjecture are there stated in detail ; but brief- 

 ly they are these : 



1st. OpjDosite seasons in the hemispheres : The identity of at- 

 mospherical constituents in all parts of the earth, notwithstanding 

 the unequal distribution over its surface, both as to place, numbers, 

 and kind, of the agents which corrupt and of those which purify 

 the air. This identity of constituents seemed to favor the idea 

 of a general and regular intermingling ; nay, the principles of ad- 

 justment which obtain in that exquisite system of compensations 

 which is displayed in the workings of the physical machinery of 

 our planet seem to call for such regular and active intermingling 

 of the fluid covering, both aerial and aqueous, of the earth as would 

 keep each element pure and make it homogeneous. Were it not 

 so, we know of physical agents which, in process of time, would 

 make both the air and the water of the two heniisj)heres quite 

 different those of the one from those of the other. Consequently, 

 if the atmosphere of one hemisphere were to become different from 

 that of the other, the air of the north would not be suited to the 

 flora or the fauna of the southern hemisphere, and conversely. 



2d. The aqueous area of the southern hemisphere is much 

 greater than that of the northern. But, notwithstanding the evap- 

 orating surface of the former so much exceeds that of the latter, 

 the amount of precipitation upon the land is very much great- 

 er in the one that exposes the smallest sea surface or source of 

 vapor. 



This circumstance had induced meteorologists, in treating of the 

 exquisite workmanship displayed in the atmospherical machinery 

 that surrounds our planet, to liken the southern hemisphere to 

 the boiler, the northern to the condenser of the steam-engine. 

 How, then, without a crossing of the winds at the calm places, 

 could the vapor be transported from one side of the equator to 

 the other? 



8d. Another link in this chain of circumstantial evidence sug- 

 gesting a crossing is in the fact that the sea water of the southern 

 hemisphere is, parallel for parallel, specifically heavier than sea 

 water of the northern hemisphere. 



As a rule, parallel for parallel, the former is the cooler, but 

 at the same temperature it is specifically heavier and therefore 



