Cjhap.p. WATER-WORKS. 307 



over, even tho' the Sides were Brick, as has 

 been commonly ufed : Yet 'tis certainly beft 

 to CJay the Bottom-, and that with extraordi- 

 nary good Clay, fuch as has been prov'd^ 

 and if it were twelve or fourteen Inches thick, 

 ftiU the better. But this amounts to a great 

 deaj of Money, and 'tis the Quality rather 

 than the Quantity that does in this Cafe 5 on- 

 ly there ought to be a tolerable Thicknefs, 

 becaufe lean Gravel or Sand will infinuate 

 and mix amongft, and in time corrode and 

 eat out that Balfamick Quality, (if I may fo 

 call it) as is in the beft of Clays. 



However, in fome forts of Ground, Clay- 

 ing at the Sides is fufRcient, (viz.') where the 

 Springs lie near, or (as I have hinted before) 

 w^here there are naturally Layers of Clay or 

 Clayey Gravel : The Workmen then (after 

 the Canal or Pond is form'd) ought to dig a 

 good deep Trench down to the bottom of the 

 Sides, and ram it a Foot thick into the 

 Trench, which will keep the Water from 

 that Horizontal Motion which it affumes ra- 

 ther than any. 



In the W^eftern Part of England, where 

 Chalk is plenty, and Clay fcarce, they chalk 

 the Bottoms and Sides of their Ponds 5 for after 

 haying brought them to a rough Level, they 

 take off their fineft Chalk, and work it with 

 Rammers till 'tis as fine as Powder, by which 

 w^orking it lies very clofe, fo that no Water 

 will enter, at leaft it does not foak out very 

 faft : This ought to be laid a Foot thick at 

 X 2 leaft. 



