Dubuque, Iowa, is supplied by a spring accidentally struck while tunneling in a neighboring drift.

At the upper basin of the Thames River there are seven springs, whose capacity is estimated at 32,000,000 gallons daily.

Liverpool, England, has four wells, with a combined capacity of 6,000,000 gallons daily.

Birmingham, England, has four wells, from which the water company derives 8,000,000 gallons daily.

Washington has over 400 wells, and Cincinnati about 300, nine of which are artesian, that were bored by private enterprise.

The deepest well in the world is near Berlin—4194 feet deep without piercing the salt formation.

WELL BORING.

The art of boring into the earth was practiced by the Chinese 2,000 years ago, the feature of their system being the percussive action of a tool suspended by a flexible rope.

The system now practiced in Great Britain, and on the Continent, is that in which the tools are attached to rods, consisting of a number of lengths, from ten to thirty feet long, joined by a separate collar, with a combined vertical and definite rotary motion, produced by a swivel joint in the upper length, or by suspending the rod to a “dog.” An ordinary well is first sunk to such a depth that the water below will rise, through the boring, into it. The object is to partly facilitate the object of boring, but chiefly to enable the pumps to be fixed without too great a length of suction. In deep wells, windlasses, driven by steam power, are used for operating the tool; the size of rod being, usually, 1¼ inch square; but for an eight foot boring, a 4½ inch square rod was used. To reduce the jarring and vibration, where borings are of considerable depth, the rods are hollow, in order to give same rigidity and resistance to torsion with less weight, and made buoyant, when working in water, by filling the rod with cork or light wood. A sliding joint, known as the “Oëuyenhausen joint,” is frequently used to bring the jarring only on that portion of the boring rod below. A shell pump is employed, in combination with the boring tool, for gathering the detritus, which obviates frequent raising of rod. Free-falling tools, guided by sliding joint, with catch or pall to raise same, are largely used. The weight of tool depends upon the depth and character of boring, that of the La Chapelle well being four tons.