64 THEORTofRAIN. 



the intenfity of heat which the diredl rays of that luminary 

 would produce. 



THUS there are an indefinite variety of appearances to be 

 produced from this fimple principle of aqueous condenfation ; 

 for, in taking the gradation from the one extreme of tranfparent 

 atmofphere to the other of the denfeft cloud, and from the fal- 

 ling of the gentleft mift and dew to the heaviefl rain, hail and 

 fnow, we have an indefinite variety of appearances, all flowing 

 from one fimple principle. 



4. Comparative EJlimate of Climates in relation to Rain. 



IT has been now obferved, that the places in which it feldom 

 or never rains are, in a manner, as nothing, and ought only to 

 be confidered, upon the globe, as a point or two, where rain, 

 fo variable in its quantity, appears to ceafe. Here, therefore, 

 may be confidered as placed the leaft quantity ; and from this 

 to the greateft quantity, there is a confiderable latitude, and an 

 indefinite gradation. 



IT will be neceffary to reduce thefe particular obfervations 

 to a generality, and thus to have fome fac"ls to which the theory 

 may be applicable. But, in order to have the theory tried by 

 thofe appearances, it will be neceffary to ftate the principles up- 

 on which, according to the theory, the differences in the quan- 

 tity of rain in each place mould depend. We may thus form 

 fome general principles, by which the natural appearances, with 

 regard to the quantities of rain, may be compared. 



IN each place of the earth, the general quantity of rain de- 

 pends upon two feparate principles, which may be varioufly 

 compounded. The firft principle upon which the formation of 

 rain depends, according to the theory, being the mixture of 

 different flreams of the atmofphere, the quantity of rain mufl 

 depend, in the firft place, upon circumftances favourable to this 

 mixture, or this meeting of different winds. 



THE 



