1899-00 



TRANSACTIONS 



12>9 



equal to the vertical distance betweeln the ground level, and the 

 lowest level of ground water. To insure this it is necessary to 

 have the mouth of the well raised a foot or more above the 

 surface of the surrounding soil, and to have the brick (or stone) 

 lining of the well backed up by a layer of puddled clay, a foot or 

 more in thickness, and extending continuously from the level of 

 the ground water quite up to the mouth of the well. 



Diagram of well; showing a backing of puddled clay, or other impermeable materia 

 ^S.between the brickwork and the porous strata through which the well is dug. 



mimm//w////i////;/w////w ;/mmw;;w/m//m^^^ 



Fig. 



4- 



A — porous strata, such as sand, gravel, loam, shale, etc B — impervious stratum, such 

 as clay, rock without flaws, etc. 



