Engineering Wonders of the World
Volume III

ARI ESIAN WELLS, AND HOW THEY ARE BORED. 343 On the tools so far enumerated all others are more or less modelled. On the Continent, coal-pit shafts of 18 feet inside diameter are bored through water-bearing strata by means of huge combination chisels and tools re- sembling those used for well-sinking, but, of course, very much larger. The lining of these shafts consists of rings of cast-iron tubbing lowered from the surface, ring after ring being bolted to the upper end of the topmost tier. In this way water-bearing rocks are cut through without the aid of pumps, and when dry rock is reached the diver about to descend a well to BELOW WATER. lower cutting edge may be sunk into it, or a water- tight joint may be made on hard rock by means of a “moss box,” a c o n tr ivance whereby a quantity of moss is com- pressed upon the rock by the weight of the cylinders. The further prog- ress of the shaft through the dry strata now reached is effected by the ordinary methods. In America an artesian basin of consider- able depth occupies a good part of the Stat© of Dakota. The water-bearing rock is a sand- stone of which the surface out- American .. Wells. croP lies aiong the foot-hills of the Rocky Mountains and around the Black Hills. The melting snows, no doubt, furnish much of the water which rises with so much force in the numerous bored wells that have been sunk in the Dakota basin. The earliest discovery was made in 1881 in the James River valley by the Chicago, Milwaukee, and St. Paul Railroad Company. They sunk a six-inch well to a depth of 920 feet, and it flowed at the rate of 830 gallons per minute. Io-day there are hundreds of artesian wells in the area of the basin, which measures 400 miles north and south, and 150 miles east and west. The wells serve vari- ously for town supply and for irrigation, but many are made to produce power. One of the chief of these power producers is situated at Woonsocket. It is 775 feet deep and only 7 inches in di- ameter, yet it yields over 4,000 gallons a minute. When its closing valve is shut, the static pressure of the water is 165 pounds to the square inch. This drops to 62 adjust a valve pounds with a 4 - inch outlet and 75 pounds with a 3-inch outlet. It drives a roller flour mill by means of a 3-foot Pelton wheel run- ning at 275 revolutions per minute with a single l|-inch jet, and saves £1,200 per annum as compared with equal steam power. Another well at Springfield is 593 feet deep, with an S-inch lining tube and a pressure of 130 pounds per square inch. This drives a flour mill by means of a 16-foot turbine rotat- ing 800 times per minute, and grinds eighty barrels of flour per day. At Chamberlain, where the sandstone was loose, and possibly the casing was put in somewhat carelessly, water began to leak up