134 E. F. PITTMA.N. 



The theory of rock pressure as a cause of flowing wells 

 was advanced many years before it received the advocacy 

 of Mr. Robert Hay. It has been ably dealt with by Mr. 

 W. H. Norton, an American geologist of high repute, from 

 whose writings 1 the following extract may be quoted : — 



"A rival theory to the hydrostatic theory was that of ' rock- 

 pressure,' which assumed that the water of artesian wells is 

 squeezed out of the aquifer by the enormous pressure of the 

 superincumbent rocks. This was answered by Arago early in the 

 19th century, but lingering in the popular mind, and again put 

 forward of late years as an explanation of the flows of petroleum 

 and natural gas, it has once more been laid by Leslie (Ann. Rept. 

 Penna. Geol. Sur., 1885), and by Orton (Geol. Sur. Ohio. Econ., 

 vol vi.). Recently it has been revived, as at least a subordinate 

 and occasional factor in artesian flows, by Professor Robert Hay. 



" Assuming a specific gravity of three times that of water for the 

 strata of a region to the depth of 600 feet, he states that at that 

 depth the pressure of the superincumbent rocks amounts to fifty - 

 two atmospheres, and that if a water-bearing stratum at that 

 depth be pierced by the drill, we should then have the rock 

 pressure of fifty-two atmospheres squeezing the water out of the 

 rock pores, and granting sufficient plasticity in the rock, and a 

 sufficient quantity of water, it must rise in the tube, which has 

 only the pressure of one atmosphere upon it. A large bore to the 

 well, and a small supply of water, would be against it reaching the 

 surface. On the other hand, a bed-rock with mobile molecules at 

 or near saturation under this enormous pressure must cause, in a 

 narrow tube a flowing well. 



"No objection need be offered to the supposition that circum- 

 stances might occur in which, for a short time, rock pressure 

 might produce a flow of water under certain assumed conditions. 

 But such occurrences must be local and temporary, as is the flow 

 from wells sometimes produced by earthquake shocks. 



1 Artesian Wells of Iowa, W. H. Norton. Iowa Geol. Sur., Vol. vi., 

 1897, pp. 132, 133. 



