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measures, are 400 feet thick, and are composed of beds of 

 clay marl and sandstone, and are quite impervious to water. 



These would prove a complete harrier to all communi- 

 cation of water from the coal beds, if it were found there. 

 At all events the sinkings would be too deep, and conse- 

 quently the expense too great for obtaining a supply at a 

 moderate cost, if it really existed. 



I have heard that a professional gentleman of this town, 

 who claims to have some knowledge of geology, and of 

 its hearings on the subject of water supply, has advised the 

 Harrington Company to sink wells somewhere near the 

 River, for the purpose of obtaining from it an unlimited 

 supply of fresh water. The freshness is to be imparted to 

 the salt water by its passage by infiltration through the 

 sandstone strata. How the gentleman has arrived at this 

 extraordinary conclusion it would be a very difficult matter, 

 I believe, to find out. 



There is no doubt of the fact that fresh water is found 

 in the strata at a very considerable depth below the level of 

 the river at low water. This, however, is easily accounted 

 for by the hydrostatic pressure of the water in the strata, at 

 a higher level, acting upon water in the lower with a force 

 proportioned to its altitude. This explains the principle 

 upon which springs of fresh water exist below the level of 

 the ocean. As long as the water remains in the strata 

 undisturbed, this condition of things will continue without 

 change, but as soon as the strata are becoming exhausted, 

 the subterranean water that thus found its way into the sea 

 is intercepted, and the vertical pressure being withdrawn a 

 reverse action will take place, and instead of the fresh water 

 flowing into the sea, the sea water will find its way through 

 the same channels inland, and brackish water will be 

 pumped up instead of wholesome and pure fresh water. 



If I mistake not, something of the kind has taken place 

 in the Harrington Company's well in Soho-street, which has 



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