Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/424

 420.

Artesian Wells are most available, and of the greatest use, in low and level districts where water cannot be obtained from superficial springs, or by ordinary wells of moderate depth. Fountains of this kind are known by the name of Blow wells, on the Eastern coast of Lincolnshire, in the low district covered by clay between the Wolds of Chalk near Louth, and the Sea-shore. These districts were without any springs, until it was discovered that by boring through this clay to the subjacent Chalk, a fountain might be obtained, which would flow incessantly to the height of several feet above the surface.

In the King's well at Sheerness sunk in 1781 through the London clay, into sandy strata of the Plastic clay formation, to the depth of 330 feet, the water rushed up violently from the bottom, and rose within eight feet of the surface. ''See Phil. Trans.'' 1784.) In the years 1828 and 1829 two more perfect Artesian wells were sunk nearly to the same depth in the Dock yards at Portsmouth and Gosport.

Wells of this kind have now become frequent in the neighbourhood of London, where perpetual Fountains are in some places obtained by deep perforations through the London