54 THEORY of RAIN. 



two ftreams of air, flowing in oppofite directions. If thofe 

 ftreams of air, therefore, fhall be fuppofed as both fufficiently 

 faturated with humidity, then, as they are of different tem- 

 peratures, there would be formed a continual condenfation of 

 aqueous vapour, in fome middle region of the atmofphere, by 

 the commixtion of part of thofe two oppofite ftreams. 



HENCE there is reafon to believe, that, in this fuppofed 

 cafe, there would be formed, upon the furface of the globe, 

 three different regions, the torrid region, the temperate, and the 

 frigid. Thefe three regions would continue flationary ; and 

 the operations of each would be continual. In the torrid re- 

 gion, nothing but evaporation and heat would take place ; no 

 cloud could be formed, becaufe, in changing the tranfparency 

 of the atmofphere to opacity, it would be heated immediately 

 by the operation of light ; and thus the condenfed water would 

 be again evaporated. But this power of the fun would have a 

 termination ; and it is there that would begin the region of 

 temperate heat, and of continual rain. , It is not probable, that 

 this region of temperance would reach far beyond the region of 

 light j and, in the hemifphere of darknefs, there wou^d be 

 found a region of extreme cold and perfect drynefs. 



LET us now fuppofe the earth as turning on its axis, in the 

 equinoctial fituation. The torrid region would thus be changed 

 into a zone, in which there would be night and day ; confe- 

 quently here would be much temperance, compared with the tor- 

 rid region now confidered ; and here perhaps there would be 

 formed periodical condenfation and evaporation of humidity, 

 correfponding to the feafons of night and day. As temperance 

 would thus be introduced into the torrid extremity, fo would 

 the effect of this change be felt over all the globe, every part of 

 \vhich would be now illuminated, confequently heated in fome 

 degree. Thus we would have a line of great heat and evapora- 

 tion, graduating each way into a point of great cold and con- 

 gelation. Between thefe two extremes of heat and cold, there 



would 



