THE EARTH, 1? 



in observing these great circulations of nature. 

 Every eye attempted to explain those appear- 

 ances ; and every philosopher who has long 

 thought upon the subject, seems to give a pecu- 

 liar solution. The inquiry whence rivers are 

 produced; w r hence they derive those unceasing 

 stores of water, which continually enrich the 

 world with fertility and verdure ; has been vari- 

 ously considered, and divided the opinions of 

 mankind more than any other topic in natural 

 history. 



In this contest, the various champions may be 

 classed under two leaders, M. de la Hire, who 

 contends that rivers must be supplied from the 

 sea, strained through the pores of the earth ; and 

 Dr Halley, who has endeavoured to demonstrate, 

 that the clouds alone are sufficient for the sup- 

 ply. Both sides have brought in mathematics to 

 their aid ; and have shewn, that long and labori- 

 ous calculations can at any time be made, to ob- 

 scure both sides of the question. 



De la Hire* begins his proofs, that rain water 

 evaporated from the sea is insufficient for the pro- 

 duction of rivers, by shewing, that rain never pe- 

 netrates the surface of the earth above sixteen 

 inches. From thence he infers, that it is impossi- 

 ble for it, in many cases, to sink so as to be found 

 at such considerable depths below. Rain water, he 

 grants, is often seen to mix with rivers, and to swell 

 their currents ; but a much greater part of it eva- 

 porates. In fact, continues he, if we suppose the 



* Hist, de 1'Acad. 1713. p. 56. 



