Chap. 6.] Cheap Mock tf draining Marjh Lands. 493 



commonly level, the water will be more eafily diffufed 

 through the foil, than it can be upon the declivity of 

 a hill. The great art, therefore, in the draining of 

 marihes is to difcover the fource, which may be looked 

 for on the brow of fome eminence which overhangs 

 them j and in may generally be found by obferving 

 where the boggy part grows narrow and angular, and 

 points as to an apex, which is the fpring whence all 

 the mifchief proceeds. When the fource is once dif- 

 covered, the water may be eafily drawn off by drains, 

 aqueducts, or pipes, according to the circumftances of 

 die cafe. The common mode of draining land by 

 cutting deep trenches, or drains, through the marfh 

 kfeif, to ferve as refervoirs for the water, is much more 

 laborious, and expenfive, and indeed feldom anlwers 

 die end propofed-, for as loon as the trenches fill, the 

 ground is rendered as fwampy as ever; and even 

 where drains are made on the principle of an in- 

 clined plane to draw off the water, they are fre- 

 quently flopped by the mud of the inarm,. and the leaft 

 ftoppage expofes the land again to at lead a partial 

 overflow. 



There are fume fprings which exhibit a very curious 

 phenomenon, a kind of tide or intermiffion, by which 

 the water at certain periods appears to rife to a conii- 

 derable height, and gradually to iiibfide. Thefe arc 

 called intermitting fprings. It was long imaginecj, 

 that thefe fountains were replenifhed by fome connec- 

 tion with the fea j that the water was frefhened by its 

 progrefs through land and earth, and that their rifing 

 and falling depended on the tide. It was, however, 

 found, that the periods of the water rifing and falling 

 in thefe fprings, did not correfpond in point of time 

 with the tides of the adjacent feas, and that the periods 

 were different in different fprings, contrary to the re- 

 gular 



