272 Springs and Artificial Fountains. 



36. According to others, these shafts can and ought to be consid- 

 ered as tubes, which show the pressure of the water upon an eartliy 

 or stony bed, in which these shafts end.* 



37. These two opinions appear to us equally admissible. In fact, 

 the labors in exploring the mines and quarries, have taught us, that 

 in certain kinds of formations the waters are subterraneously diffused 

 in veins, streams, and sometimes even in torrents more or less pow- 

 erful, through the crevices, fissures and natural perforations of the 

 interior of the bed of rock; while in other kinds of formations, the 

 waters form level sheets, more or less abundant, between the beds 

 of sand, of earth, or of stone, permeable and impermeable. 



38. The grand calcareous masses of tlie chains of the Alps and 

 of Jura, present numerous examples of these torrents, or subterra- 

 nean streams, which have their sources or origin in the high moun- 

 tains, and which after a longer or shorter course, form the admirable 

 fount&ins of Vaucluse, Laisse, FOrbe, Sassenage, &c. &z;c. Some 

 quarries in Paris and the environs, offer frequent examples of vesti- 

 ges of streams, or subterrane-an currents, which have formerly passed 

 through tlie calcareous mass, at different heights, by the means of 

 fissures and crevices; which generally intersect it in all directions. 



39. The manner in which the springs exist, which are extended 

 along the declivities of hills, to an almost constant height, in forma- 

 tions and beds, particularly in those of alternate formations of sand 

 and clay, establish and characterize this disposition of the waters, 

 which we have said is in a sheet, and whose origin is attributable, 

 either to the subterranean effusions, which proceed from more ele- 

 vated regions, or to the infiltrations of snow and rain water, which are 

 arrested by these beds of clay. 



40. This sheet of water has been assimilated to a bed of clay, of 

 sand, or of chalk. If the water is considered as placed between two 

 curved surfaces, like two cups or basins, of different diameters, 

 whose superior borders shall be in the same plain, or irregularly den- 

 ticulated, or in part closed, the liquidity of the water is the cause of 

 the pressure, which the tube formed by boring measures; but if it is 

 supposed that instead of a sheet of liquid water, it was a sheet of ice, 





* Mineral and thermal waters, rise to the surface of the earth, from the interior 

 of primitive formations in consequence of the disengagement of gas and compressed 

 vapors, which press and rest upon the surface of these subterranean waters. This 

 has been perfectly demonstrated by M. JBerthier, chief encineer of the mines. 



