242 On the Anhnal Calculus. 
owing to the tartarine Qiiality with which they 
are impregnated. 
ij. The Comb Water is not filtrated thro' 
a great Depth of Earth before it comes to the 
Gravel, which is alfo the Cafe of the Canter- 
bury Waters ,• and of thofe at Havering 
Bower. 
1 6 . As Comb-Hill is Gravel in a manner to 
the Surface, and the Springs (many of which 
I have feen opened) arife at the Brow of the 
Hill out of that Gravel, the Water muft par- 
take greatly of the Nature of Rain Water; 
fince the Dew and Rain which falls on that 
Hill, receives probably no other Alteration, in 
percolating thro’ the Gravel only, than in com- 
ing out more pure and free from Sulphur than 
Rain Water is. 
17. On comparing the Quantity of Sedi- 
ment remaining after the Evaporation of e-^ 
qual Quantities, viz, thirty four cubic Inches 
of Rain Water and Comb Water, I found ic 
exadly the fame, viz. two Grains, which is 
in proportion to the Weight of Water as i to 
4445 ; And the Sediment, of Havering Bower 
Water was nearly in the fame Proportion. 
The Method I made ufe of to do this with 
Accuracy was by cutting ofE the upper part of , 
Florence 
