Deep springs are fed by the waters falling upon and soaking down to great depths, and find their way to the surface through some fault, upheaval or other great geological disturbance, or between some impermeable strata. The most copious springs are in the tertiary strata, and the law, as regards their abundance, is “the rarer the visible springs may be, the more copious they would be found.” The permanence of the springs can only be relied upon after careful gauging, extending over several years. Wells may be separated under the following divisions: Shallow, or dug wells. Ordinary deep, or pump wells. Artesian wells. “Shallow and deep wells are those which are sunk through a permeable stratum, and form, as it were, reservoirs, into which the land springs may filter and accumulate; whilst artesian wells are those which are sunk through an impervious upper stratum, to reach a subterranean water-bearing stratum lying, in its turn, upon an impervious upholding bed. In the former cases, the quantity of water obtainable is simply that which can filter through the sides of the well to replace the water removed, or which may accumulate in any reservoir formed below; whilst, in the latter case, the quantity obtainable will depend simply upon the power of the water-bearing stratum to transmit water. “In the case of deep-seated wells, the probable yield of water must depend, primarily, upon the area of permeable strata likely to affect the supply, and upon the facilities those strata may offer for the passage of water; and, secondly, upon the rate of consumption which takes place in the neighborhood, for the quantity of water which any particular stratum can supply is only a limited quantity; so that, evidently, if the water be taken at one point, no more will remain for the other.”--(Hydraulic Engineering, Weale’s Series.) The above fact is illustrated, practically, in London, where the water line of the chalk formation has been permanently lowered to the extent of fifty or sixty feet below Trinity high-water mark; and it is even stated that the level of the water in the wells, near the summit of this formation, rises, on the Monday morning, in consequence of the cessation of pumping in London during the Sundays. The experience of Liverpool corroborates this fact: that the Windsor well, having a depth of 210 feet, affected the surrounding wells to a maximum distance of a mile and three quarters. The celebrated engineer and originator of the well system of Liverpool, Robert Stephenson, from long experience and careful observation, offered the following conclusions (from Hughes water-works): “That an abundance of water is stored up in the new red sandstone, and may be obtained, by sinking shafts and driving tunnels, about the level of low water. “That the sandstone is generally very pervious, admitting of deep wells drawing their supply from distances exceeding one mile.