A suitable arrang-ement must be provided for paying out the rope as the boring--tool descends. A clamp is attached to the cable, and the man in charge, by turning the clamp, twists the rope, and thus turns the bit hori zontally about one-fifth of a.revolution after each stroke until six or eight complete revolutions have been made in one direction. He then reverses the motion, making an equal number of turns in the opposite direction.
—After drilling a few feet, the string of tools is lifted out by means of the cable, to allow of the removal of the debris. This is done with the sand-pump, which is a sheet-iron cylinder, say 4 inches in diameter and from 4 to 6 feet long, provided at its foot with a valve open ing upward. This pump is lowered to the bottom of the bore and filled with the mixed water and debris by churning it up and down a number of times. The pump is then lifted out and emptied. The string- of tools is ao-ain lowered and the drillino- resumed. The debris must be removed after each 3 or 5 feet of drilling.
Sprelding.—The same operations are followed in drilling through the earth before the rock is reached. This is called " spudding." In this case the sides of the bore-hole must be protected from caving in. For this purpose a wrought-iron pipe ,14/. of an inch thick and of such a diameter as to fit the hole closely, is inserted, and is driven down with a heavy oaken maul as the drilling- proceeds. One end of the maul is attached to the lower end of the cable which during drilling supports the string of tools, and is repeatedly lifted and dropped upon the head of the tube, which is protected by a cast-iron " driving-cap." The foot of the tube is shod with a steel cutting-edge ring-. When the tube has been driven as far as it will readily go, the maul is removed from the end of the rope, the string of tools substituted, and the drilling resumed inside the pipe. The pipe is put together in lengths of from 8 to IS feet, and the drilling and pipe-driving proceed alternately until the rock is reached and the foot of the pipe forced into it far enoug-h to shut off quicksand or surface-water. For overcom ing special difficulties there are employed appropriate tools and devices which need not here be considered.
Boring': Derrick. —For wells from i000 to 3000 feet deep there is used a stationary machine with a walking-beam, similar to the machines employed in the oil-regions of Pennsylvania. A square pyra midal derrick is erected, 74 feet high, 20 feet square at the base, aud 4 feet square at the top. The four corner leg-s, made of stout planks spiked tog-ether,
are strongly braced by horizontal and diagonal timbers. The timber walking-beam is 26 feet long, 12 inches wide, and 26 inches deep at the middle, and is pivoted to the top of a stout wooden post 12 feet high, called and motive-power is a fifteen-horse-power steam-engine, which, by means of a belt and pulley, crank, and pitman working at one end of the walking-beam, gives to the latter its see-saw motion. To the other end of the beam, and immediately over the well, is suspended, by means of a hook, a " temper-screw." This is composed of two bars of iron (5.8 by 2 inches in diameter and 2 feet long), hung 2 inches apart, fastened together at their top ends, at which point there is an eye, which is suspended on the walking-beam hook. At the bottom of the two bars there is a sleeve-nut, and between the two bars and passing through the nut is a screw 5 feet long, at the bottom of which there is a bead carrying a swivel, a set-screw, and a pair of clamps. These grasp the cable (2 or 21 inches thick) which carries at its lower end the string of tools. This, for a 2000-foot well, consists of a steel bit 3 or 4 feet long, weighing from two hundred to four hundred pounds; an auger-stem of 4- or 5-inch round iron from 24 to 3o feet long, weighing from twelve hundred to twenty-one hundred pounds; steel-lined drill-jars 8 feet long, weighing from six hundred to seven hundred pounds; a sinker-bar of round iron, of the same diameter as the auger-stem, 12 feet long and weighing from six hundred to eleven hundred pounds; and a rope-socket feet long, weighing two hundred pounds. The total length of the string of tools is from 5o to 6o feet; total weight, three thousand pounds, or, for an 8 inch bore in the hardest rock, four thousand pounds. The sinker-bar is added to give additional weight in lowering the string of tools and in working the drill-jars. The other tools are similar in form to those above described. (See pi. 53, figs. The is wound round a drum called a " bull-wheel shaft," at the foot of and inside the derrick. While drilling is going on, the cable passes from the bull-wheel shaft loosely over the sheave at the top of the derrick and down to the clamps at the lower end of the temper-screw on the end of the walking-beam. As the drilling- progresses the temper-screw is turned or fed out by the man in charge, who by means of a clamp twists the rope so as to change the position of the bit after each stroke.