rHEORTcfRAIN. 59 



lubited upon fo large a fcale, that it is almoft impoflible to have 

 them explained in any other manner. Let us examine thofe cir- 

 cumftances which cannot be miftaken, and which may be fu- 

 ficient for deciding in this queftion. 



FROM the eaflto the weft of this great tropical continent of Afia 

 and Africa, the rivers inform us, that it rains in the feafon of the 

 fummer folftice ; and that, on the contrary, fair weather is here 

 produced by the removal of the heating caufe. We cannot fup- 

 pofe,that heat is an immediate caufe for the condenfation of aque- 

 ous vapour ; nor can we fuppofe that this efFecl mould not be pro- 

 duced by cold ; for this would be no lefs than to fuppofe in na- 

 ture an inconnftency, which never has appeared. While, there- 

 fore, we allow the laws of nature to be fleady, the effe<5l of the 

 lummer fun, in this continental fituation, muft be, to elevate 

 the heated air, and to have its place fupplied by that which has 

 come, fraught with aqueous vapour, from the neighbouring 

 feas : But being arrived here, upon this heated continent, 

 this humid air muft be elevated into the higher regions of the 

 atmofphere, and either be tranfported from thence towards the 

 polar regions, there to be gradually condenfed, as the cooling 

 caufe takes place, or it muft here fall in rain, by finding a caufe 

 for its condenfation. Upon the fir ft fuppofition, no rain mould 

 be found here during the fummer feafon ; or the rivers, by 

 which we are to judge of this event, mould be at the loweft af- 

 ter fummer. But, as the oppofite of this is true, the rivers be- 

 ing then in their fwelled ftate, it neceflarily follows, that the 

 humid atmofphere, tranfported from the fea, muft have its 

 water condenfed upon this heated continent in the fummer fol- 

 ftice ; and there is not, at prefent, any other principle known, 

 by which this operation might take place, or any other theory 

 by which thofe natural appearances of periodical rain might 

 be explained, 



THE fummer fun, which proves a caufe of rain in certain rer 

 gions, where feas, affording great evaporation from their heat, 



H 2 are 



