i4 DRINKING POOLS. p 



There is little difficulty in making a pit 

 hold water with clay alone ; provided it be 

 kept up full to the brim ; but once emptied, 

 its retentivenefs is loft. There are two caufes 

 of this lofs of retentivenefs : — the cracking 

 of the clay by droughty and its being liable^ 

 whenever the water fubfides, to be per- 

 forated by ivormSy which prefently convert 

 the bafon into a filter, and for ever afterward 

 deftroys its retentivenefs. It is therefore ne- 

 ceirary that thofe two enemies fhould be 

 guarded againft. 



To o-uard againll the latter a coat of lime 

 is fpread under the clay : above it a coat of 

 earth, and over all a covering of JloT^es is 

 laid, for the double purpofe of guarding 

 againft drought, and for preventing the feet 

 of cattle from injuring the clay ; which 

 alone is the caufe of retentivenefs ; and on 

 the proper working of which the art princi- 

 pally depends. 



But many other particulars are requifrte to 

 be known before the art can be fufficiently 

 undeillood to be pradiiled with certainty. 



1. The Run, or collecting 4. Claying. 



furface. 5. Covering. 



2. The Rcfcrvoir. 6. Timeof making. 



3. L iming. 7. Coll. 



I. The 



