258 



DRAINING 



Sect. XI. 1.2. 



k 



of geology has been fludied, and in fome mcafure difFufed amongfl; the 



people. 



Lands in refpedl to the method of draining them may be divided 

 into two fituations ; thofe which lie fo high, that the water can de- 

 fcend from them, if it be properly colle6led and conduced ; and 

 thofe which lie fo low as to command no fall, fome of which are 

 even below the level of the fea, 



2. In regard to the former it generally happens, that the waters from 

 the fprings beneath the foil have not a free paiTage to the rivers in 

 their vicinity; the nature of fprings fliould therefore be previoufly 

 iinderflood. Many modern phllofophers have endeavoui'ed to fliew, 

 that all the continents and iflands of the world, as well as the hills^ 

 Vv'hich embofs their fnrfaces, have been raifed out of the primeval 

 ocean by fubterraneous fires. This appears from the quantity of fea- 

 Ihells, which form innumerable mountains ; and from the fifliires in 



the rocks, of which they con fifl: ; the quantity of volcanic produc- 

 tions all over the world ; and the numerous remains of craters of vol- 



I 



canoes ni mountainous countries. 



Hence the ftrata, which compofe the fides of mountains, lie fl 



D 



downward 



d one or two or more of the external ft 



caching to the fummit, wh 



d 



third fl 



a more 



fe 



fed up, the fe 

 here expofed t< 



day. This may be well reprefented by forcibly thrufling a very 



Pi 



ment through fome folds of paper, a bur will be raifed 

 mofl: leaf landing; hig-hefl in the center of it. Or if a 



einal elevation of an extenfive mountain the lowefl: flratum fliould 

 not at firfl: (land higher in the center of the fummit, it Vv'ould in 



fo by fome of 



u 



PP 



ftrata of the mountain being 



gradually wadied away by rains into the valle^= 



rivers. 



O 



ft flratum. which is colder, as it is more elevated, the d 



fed in large q 



d fliding down pafs und 



ft, or fecondj or third flratum, which compofe the fid 



:r th 



of th 

 hill 



\ 



•• ' 



