Chap. 6.3 Ccntroverfy concerning Rivers. 495 



the fpring at D, on the principle explained in the pre- 

 ceding paragraph, and the whole phenomenon will be 

 eafily accounted for. 



With any perfon who has carefully obferved the 

 courfe of rivers, and traced them to their fonrces, 

 there can be little doubt that they are formed by the 

 confluence of fprings, or of the little dreams or rivulets 

 that ififue from them ; with perhaps the exception of 

 thofe rivers which proceed from ..lakes, where the 

 refervoir is ready formed, and generally by the fame 

 means. 



In the beginning of the prefent century, the philo- 

 fophical world was agitated by a debate concerning 

 the origin of thofe waters which are neceflary for the 

 fupply of rivers, &c. one party contended ftrongly for 

 the existence of a large mafs of water within the bow- 

 els of the earth, which fupplicd not only the rivers but 

 the ocean icfelf j at the head of thefe we may place the 

 ingenious but fanciful Burnet. The French philofo- 

 phers, on the contrary, afferted, that the waters of the. 

 ocean were conveyed back by fome ftibterraneous 

 pafiages to the land, and being filtrated in their paf- 

 iage, returned again to the fea in the courfe of the 

 rivers ; but this opinion appears contrary to all the 

 known principle of hydroftatics. 



In oppofition to thefe hypothefes, our iliultrious 

 countryman Halley contended that the procefs of eva- 

 poration, and the immenfe depofition of water in con- 

 iequence of it, was fully adequate to the whole fupply. 

 If, indeed, we confider the immenfe quantity of water 

 which is continually carried up into the atmofphere by 

 evaporation, as ftated in a former chapter, and confi- 

 der that this is a procefs which is continually going on, 

 not only from the ocean but from the rivers them- 

 felves, and from the whole furface of the earth, we 



lhall 



