Artesian wells are named after the French Province of Artais, where they appear to have been first used on an extensive scale.

They are perpendicular borings into the ground through which water rises to the surface of the soil, producing a constant flow or stream. As a location is chosen where the source of supply is higher than the mouth of the boring, the water rises to the opening at the top. They are generally sunk in valley plains and districts where the formation of the ground is such that that below the surface is bent into basin-shaped curves. The rain falling on the outcrops of these saturates the whole porous bed, so that when the bore reaches it the water by hydraulic pressure rushes up towards the level of the highest portion of the strata.

The supply is sometimes so abundant as to be used extensively as a moving power, and in arid regions for fertilizing the ground, to which purpose artesian springs have been applied from a very remote period. Thus many artesian wells have been sunk in the Algerian Sahara which have proved an immense boon to the district. The same has been done in the arid region of the United States. The water of most of these is potable, but a few are a little saline, though not to such an extent as to influence vegetation-

Artesian Well (D) in the London Basin.

The hollows in which London and Paris lie are both perforated in many places by borings of this nature. At London they were first sunk only to the sand, but more recently into the chalk. One of the most celebrated artesian wells is that of Grenelle near Paris, 1,798 feet deep, completed in 1841, after eight years' work. One at Rochefort, France, is 2,765 feet deep; at Columbus, Ohio, 2,775; at Pesth, Hungary, 3,182, and at St. Louis, Mo., 3,843 1/2. Artesian borings have been made in West Queensland 4,000 feet deep. At Schladebach, in Prussia, there is one nearly a mile deep.

As the temperature of water from great depths is invariably higher than that at the surface, artesian wells have been made to supply warm water for heating manufactories, greenhouses, hospitals, fishponds, etc. The petroleum wells of America are of the same technical description. These wells are now made with larger diameters than formerly, and altogether their construction has been rendered much more easy in modern times.

Boring in the earth or rock for mining, geologic or engineering purposes is effected by means of augers, drills or jumpers, sometimes wrought by hand, but now usually by machinery, driven by steam or frequently by compressed air.

In ordinary mining practice a bore-hole is usually commenced by digging a small pit about six feet deep, over which is set up a shear-legs with pulley, etc. The boring rods are from ten to twenty feet in length, capable of being jointed together by box and screw, and having a chisel inserted at the lower end. A lever is employed to raise the bore-rods, to which a slight twisting motion is given at each stroke, when the rock at the bottom of the hole is broken by the repeated percussion of the cutting tool. Various methods are employed to clear out the triturated rock.

The work is much quickened by the substitution of steam power, water power, or even horse power for manual labor. Of the many forms of boring machines now in use may be mentioned the diamond boring machine, invented by Leschot, a Swiss engineer. In this the cutting tool is of a tubular form, and receives a uniform rotatory motion, the result being the production cf a cylindrical core from the rock of the same size as the bore or caliber of the tube. The boring bit is a steel thimble about four inches in length, having two rows of Brazilian black diamonds firmly embedded therein, the edges projecting slightly. The diamond teeth are the only parts which come in contact with the rock, and their hardness is such that an enormous length can be bored with but little appreciable wear.