390 



ARTESIAN WELLS. 



[Ch. XVII. 



passed through. 19 feet of gravel, 242£ feet of clay and loam 

 and 67^- feet of chalk, and the water then rose to the surface 



om 



Northnmberla: 



above Chiswick, the borings were carried through a still 

 greater thickness of incumbent strata down to the chalk, 

 which was reached at the depth of 620 feet, when a consider- 

 able volume of water was obtained, which rose 4 feet above 

 the surface of the ground. In a well of Mr. Brooks, at 

 Hammersmith, the rush of water from a depth of 360 feet 

 was so great, as to inundate several buildings and do con- 



's 



b 



sufficient 



as 



obtained to turn a wheel, and raise the water to the upper 

 stories of the houses. f In 1838, the total supply obtained 



from 



London was estimated at six million 



gallons a day, and, in 1851, at nearly double that amount, 

 the increase being accompanied by an average fall of no less 

 than two feet a year in the level to which the water rose. 

 The water stood commonly, in 1822, at high-water mark, 

 and had sunk in 1851 to 45, and in some wells to 65 feet 

 below high-water mark. J This fact shows the limited ca- 

 pacity of the subterranean reservoir. 



In the last of three wells bored through the chalk at Tours, 

 to the depth of several hundred feet, the water rose 32 feet 

 above the level of the soil, and the discharge amounted to 



300 cubic yards of water every twenty-four hours. § By way 

 of a scientific experiment, the sinking of a well was com- 

 menced at Grenelle in the suburbs of Paris in 1834, which 

 had reached, in November 1839, a depth of more than 1,600 



The 

 if 



English feet, and yet no water ascended to the surface, 

 government were persuaded by M. Arago to persevere 

 necessary, to the depth of more than 2,000 feet ; but when 

 they had descended above 1,800 English feet below the 

 surface, and reached the upper greensand, the water rushed 

 up through the boring, which was about 10 inches in dia- 

 meter at its upper, and 6 at its lower extremity. The dis- 



* 



Sabine, Journ. of Sci. No. xxxiii. 



p. 72. 1824. 



j Prestwich, p. 69. 



Bull, de la Soc. Geol. de France 



f Hericart de Thury, ' Puits Pores/ torn. iii. p. 19-1. 



p. 49. 







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