The yield at the mouth was greatly decreased when raised through a tube 25 ft. high; a like result followed at Grenelle, where the yield was 440 gallons per minute at the surface, but decreased to 135 gallons when forced through a tube 33 ft. high. That these two wells, though two miles apart, drew their supply from the same source, is evident both from their temperature, 82° F. in each, and from the fact that the opening of the Passy well reduced the flow at Grenelle from 135 to 100 gallons per minute, though it is anticipated that by forcing the water at Passy through a still higher tube the yield at Grenelle may be increased. This dependence of several wells upon one source is shown also in the Pennsylvania oil region, where the water from one well, when not pumped out, often finds an exit through the tubes of those adjoining. The work on both the above-mentioned wells was much delayed by accidents. When that at Grenelle was at a depth of 1.254 ft., the drill broke off and fell with 270 ft. of rods to the bottom; 15 months were spent in breaking these and removing the pieces. The tubing in the Passy well was also burst by the external pressure of sand and water, and had to be removed and new tubes inserted, retarding the work for many months.

At Kissingen, Bavaria, there is a well 1,878 ft. deep, the last 138 ft. of which passes through rock salt. The water, which flows from it at the rate of 100 cubic feet a minute, contains 3 1/2 per cent. of salt; its temperature is 66° F., and the whole cost of boring was about $33,000. - Artesian wells are of peculiar value upon desert plains, and those vast prairies that rest upon porous limestone formations, through which the surface water finds its way and is lost. In May, 1858, M. Jus, a French engineer, commenced boring for water in the desert of Sahara, and on June 19 a well was sunk, from which there flowed a steady stream of pure water, having a temperature of 61° F., at the rate of 1,000 gallons per minute. Up to the present time (1872) over 75 wells have been bored in that desert, yielding an aggregate of 600,000 gallons an hour. The effect of this abundant supply of water upon the once barren soil ,of the desert is plainly apparent; two new villages have been built in the midst of former solitudes, 150,000 palm trees have been planted in more than 1,000 new gardens; the oases of Tamelhat, Oum Thior, and Shegga have each their wells yielding from 25 to 1,000 gallons per minute.

A promising feature in these wells is that water is reached at a comparatively slight depth, the one in the oasis of Sidi Nached being hardly 200 ft. deep. There is also a well at Bourne, England, which, though but 92 ft. deep, yields 557,000 gallons of pure water per day, and the pressure is sufficient to supply the town and force a stream above the highest roofs. The proprietors of the Continental hotel, Philadelphia, have lately completed a well, 8 inches in diameter and only 200 ft. deep, which supplies them with 50,000 gallons of pure water per day. - The success attending the work of the French engineers in Africa is one of great promise to those who would undertake the irrigation of the rich plains of the Colorado desert; and already a well bored by direction of the Pacific railway company at Point of Rocks, 805 m. W. of Denver, in the midst of the alkali district, furnishes abundant water for the engines on that road, the water rising to within 11 ft. of the surface. In 1855 the United States government sent out an expedition, under command of Capt. Pope, for the purpose of boring for water in the Llano Estacado, near the borders of Texas and New Mexico. The first well was sunk at a point 15 m. due E. of the river Pecos, on the 32d parallel of latitude.

At the depth of 360 ft. the first stream of water was struck, which rose to the height of 70 ft. in the tubing; at 641 ft. a second stream was struck, which rose 400 ft. Five miles E. of this point a second well was bored to the depth of 860 ft., in which the water rose 750 ft. - Of the artesian wells in the United States, those at St. Louis, Louisville, and Charleston are among the most important, both from their extreme depth and the difficulties attending the sinking. The well at St. Louis was completed at the expense and under the direct supervision of William II. Belcher of that city. An interesting account of its progress is given by A. Litton, M. 1)., in the "Transactions of the Academy of Science of St. Louis," vol. i., No. 1, 1857. The boring of this well was begun from the bottom of an open well 30 ft. deep in the spring of 1849. The bore to the depth of 219 ft. was 9 in. in diameter, then 5 1/2 in. for 731 ft. further, and continued at 3 1/2 in. till the full depth, 2,199 ft., was reached.. At 550 ft., the top of a limestone layer, the water became salty; 200 ft. below this, in a layer of shale, it contained 1 7/8 per cent. of salt; and at 965 ft., below a bed of bituminous marl, 2 1/2 per cent.

At the depth of 1,179 ft. the hardest rock was encountered, being a bed of chert 62 ft. thick. The work was stopped on March 12, 1854, in silicious and clayey beds belonging to the lower Silurian formation. The water is at present discharged through a 20-inch pipe at the rate of 75 gallons per minute; it is only fit for medicinal purposes, having a strong odor of sulphuretted hydrogen, and containing over 8 per cent. of mineral matter, including 6 per cent. of salt; its temperature is even at 73.4° F. The total cost of this work exceeded $10,000. The well at Louisville, Ky., has a 3-inch bore, and is 2,086 ft. deep. The water flows from it at the rate of 330,000 gallons per day, and with a force equal to 10-horse power. It is perfectly clear, though highly charged with mineral substances, being similar in composition and medical properties to the celebrated- ' Kissingen waters, and the Blue Licks of Kentucky. - Of all the wells sunk in the United States, none is so remarkable for the difficulties encountered and successfully overcome as that at Charleston, S. C. Since 1824 five attempts have been made by the city govern-ment to obtain good water by this means.