As the contents of the water-hole or well are pumped out, they are immediately replenished from the surrounding disgusting mixture, and it is not therefore very surprising to be assured that such wells do not become dry even in summer. Unfortunately, excrementitious liquids, especially after they have soaked through a few feet of porous soil, do not impair the palatability of water; and this polluted liquid is consumed from year to year without a suspicion of its character. Our acquaintance with a very large portion of this class of potable waters, has been in consequence of the occurrence of severe outbreaks of typhoid fever amongst consumers of this character of water. “The samples of water from deep unpolluted wells were obtained from wells or bore-holes of a depth rarely less than 100 feet, and reaching in one case 1,285 feet. In many cases these wells were partly or wholly supplied by surface-polluted water. Such water, when it penetrates only to shallow wells still retains a considerable proportion of its polluting organic matter in an unoxidized condition: but when it descends through one hundred feet or upwards of porous soil or rock, the exhausted filtration to which it has been subjected in passing downwards through so great a thickness of material, and the rapid oxidation of the dissolved organic matters in a porous and aerated medium, afford a considerable guarantee that all noxious constituents have been removed.”--(Rivers Pollution Commission, 1874.) “Deep wells may become polluted, either by admission of soakage from the superficial strata into the shaft of the well, or by access of polluted water through open fissures in the rock in which the well is sunk.”--(Rivers Pollution Commission, 1874.) “Even where wells are sunk to great distance (one was sunk at Bondy, near Paris, to a depth of 247 feet), the surrounding soil is not free from danger of pollution by the soaking of the foul liquid into the side of the well.”--(Fifth report Massachusetts State Board of Health.) The following table shows the average analysis of ten worst examples of well water (parts in 100,000 parts): AV. CARBON NITROGEN DEPTH. ORGANIC. ORGANIC. CHLORINE. HARDNESS. Shallow wells, -- 1.560 .241 16.56 63.24 Deep wells polluted, -- .363 .092 9.45 36.27 Deep wells unpolluted, 380 .151 .032 14.14 27.4 ARTESIAN WELLS. Artesian is the name applied to water-springs rising above the surface of the ground by natural hydrostatic pressure, or boring a small hole down through a series of strata to a water-bearing bed inclosed between two layers. It was first practiced in 1100, in province of Artois, France, whence it derives its name.