by the Fault. (See Pl. 67. Fig. 2, d, and Pl. 69. Fig. 2, H. L.)
Besides the advantages that arise to the whole of the Animal Creation, from these dispositions in the structure of the Earth, whereby natural supplies of water are multiplied almost to infinity over its surface, a further result, of vast and peculiar importance to Man, consists in the facilities which are afforded him of procuring artificial wells, throughout those parts of the world which are best adapted for human habitation.
The Causes of the rise of water in ordinary artificial wells, are the same that regulate its discharge from the natural apertures which give origin to springs; and as both these effects will be most intelligibly exemplified, by a consideration of the causes of the remarkable ascent of water to the surface, and often above the surface, in those peculiar perforations which are called Artesian Wells, our attention may here be profitably directed to their history.
Artesian Wells.
The name of Artesian Wells is applied to perpetually flowing artificial fountains, obtained by boring a small hole, through strata that are destitute of water, into lower strata loaded with subterraneous sheets of this important fluid, which ascends by hydrostatic pressure, through pipes let down to conduct it to the surface. The name is derived from Artois (the ancient Artesium,) where the practice of making such wells has for a long time extensively prevailed.[1]
- ↑ The manner of action of an Artesian Well is explained by the Section Pl. 69. Fig. 3, copied from M. Hericart de Thury's representation of a double Fountain at St. Ouen, which brings up water, from two water bearing strata at different levels below the surface. In this double fountain, the ascending forces of the water in the two strata A and B are different; the water from the lowest stratum B rising to the highest level A; that from the upper stratum A rising only to a'. The water from
