Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/427

 Rh and will afford abundant supplies of water for agricultural and domestic purposes and sometimes even for moving machinery. The quantity of water thus obtained in Artois is often sufficient to turn the wheels of Corn-mills.

In the Tertiary basin of Perpignan and the chalk of Tours, there are almost subterranean rivers having enormous upward pressure. The Water of an Artesian well in Roussillon rises from 30 to 50 feet above the surface. At Perpignan and Tours, M. Arago states that the water rushes up with so much force, that a Cannon-ball placed in the Pipe of an Artesian Well is violently ejected by the ascending stream.

In some places application has been made to economical purposes, of the higher temperature of the water rising from great depths. In Wurtemberg Von Bruckmann has applied the warm water of Artesian wells to heat a paper manufactory at Heilbronn, and to prevent the freezing of common water around his mill wheels. The same practice is also adopted in Alsace, and at Canstadt near Stuttgard. It has even been proposed to apply the heat of ascending springs to the warming of green houses. Artesian wells

These theoretical Results can never occur to the extent here represented, in consequence of the intersections of the strata by valleys of Denudation, the irregular interposition of Faults, and the varying conditions of the matter composing Dikes.

If a valley were excavated in the stratum M below A″, the water of this stratum would overflow into the bottom of this valley, and would never rise on the side of the fault so high as the level H.

Wherever the contact of the Dike H, L, with the strata M, N, 0, P, Q, R, that are intersected by it, is imperfect, an issue is formed, through which the water from these inclined strata will be discharged at the surface by a natural Artesian well; hence 9, series of Artesian springs will mark the line of contact of the Dike with the fractured edges of the strata from which the water rises, and the level of the water within these strata will be always approximating to that of the springs at H; but as the permeability of Dikes varies in different parts of their course, their effect in sustaining water within the strata adjacent to them, must be irregular, and the water line within these strata will vary according to circumstances, between the highest possible levels, A, B, C, D, E, and the lowest possible level H.