CHAP. II. 



ARTESIAN WELLS. 



45 



We see, too, that on this property of the equilibrium, of liquids 

 in communicating vessels the construction of artificial fountains 

 which adorn parks, gardens, and public places, &c., as well as natural 

 springs themselves, depend. 



FIG. 24. A fountain. 



Now an artesian well is nothing more than an aperture made 

 through the upper strata of the earth and descending to different 

 depths, according to the geology of the district, to search for sheets of 

 subterranean water imprisoned by beds impenetrable to water. These 



. Jfo/p/- 



1 ravins s-miat Tnjn 2nsuv JSar-s 



Tlaftan. 



nsyuv Sar-ssa/ic Tit T.ASGBIS 



FIG. 25. Geological section of the basin of the Seine, between Paris and Langres 



sheets of water follow the windings and inclinations of the strata ; it 

 is necessary, in order that the water should rise in the wells, that 

 there be between the point attained by the boring and the level of the 

 sheet of water a certain difference of height. An example of this fact 



