the telegraph, extends to the derrick and passes around a similar pulley nn fixed upon the headache post z, also called a "life preserver." As its name indicates, the headache post is designed to save the driller a headache, or perhaps his life, in case the wrist-pin should break or the pitman fly off of it while drilling, thus causing the derrick end of the walking beam to drop under the great weight of the suspended drilling tools, and endangering the safety of all within reach. This post is set upon the main sill immediately under the walking beam, so that if such an accident occurs the walking beam can fall but a few inches and do no harm. The pulley nn and that fixed upon the headache post being thus connected, the movement of one communicates a like motion to the other, and the driller by placing his hand upon the derrick-pulley can operate the throttle valve and start or stop the engine, and decrease or increase its speed at pleasure, without leaving his position. The reverse link pp is also operated from the derrick by the cord 99, which passes over two pulleys, one fixed in the engine house and the other in the derrick. The band wheel m receives its motion direct from the driving pulley of the engine, to which it is connected by the belt oo. On, or near, the end of its shaft o, is the bull-rope pulley n, and to its other end is fastened the arm or crank o'. In this arm a number of holes are drilled for the reception of the adjustable wrist-pin p, which thus may be easily moved from one hole to another to regulate the length of the stroke required in drilling or pumping.

As the band wheel communicates motion through the pitman q to the walking beam while drilling, to the bull wheels bb, by the bull rope rr, while running up the tools, and to the sand-pump reel by the friction pulley w, while sand-pumping, and as these movements are all used separately and at different times, it is necessary that the machinery be so constructed in its different parts that connection may be quickly made or broken, and one kind of motion substituted for another at pleasure.

The sand-pump reel w is put in motion by pressing on the

lever v, which is joined by the connecting bar u to the upright lever t. This brings the face of the bevelled pulley w into contact with the face of the band wheel. It is simply a friction pulley, and can be thrown in or out of gear, no matter at what speed the band wheel may be revolving.

For a fuller illustration and explanation of the details of Figs. 1 to 3 (Plate II) we annex figures representing a complete set of irons belonging to a carpenter's rig.

Fig. 18.-Walking-beam stirrup.

Fig. 19.-Bolts for securing this by a wooden cap to walking beam.

Fig. 20 and Fig. 20a.-Boxes for band wheel shaft.
Fig. 21.-Band-wheel shaft, arm and flanges.

Fig. 22.-Centre irons for walking beam and samson posts. Fig. 23 and Fig. 23a.-Bolts for securing the saddle to walking-beam.

Fig. 24.-Derrick or crown pulley.

Fig. 25.-Walking-beam hook, to hold temper screw.
With the rig built, and the boiler and engine set up,

the

Plate II) was first put down to the bed rock, through the surface clay or gravel constituting the unconsolidated deposit of drift lying above the upper stratum of rock. Where it became necessary to go down several hundred, instead of several feet before the rock was reached, as is often the case in valleys, a pipe was driven down through the soft formation. This is the general practice now; the first section of a well from the surface of the ground to the first solid rock consisting of a driven pipe eight inches in diameter or larger. This is necessary to keep the earth from caving and choking the well, or the surface water from seeping into it and giving trouble. The drive pipe is put down in exactly the same way as piles are driven; the derrick serving as support for the pipe, and as a guide for the heavy maul as it goes down. This pipe has to be cleared out in the same manner as the bore that is afterwards carried down through the rock.

The hole through the rock is now begun. If the driven pipe is long enough, the work is started and carried on regularly; but frequently there is not room to start off with a full string of tools, as they require at least 60 feet before they can begin their work. In such cases the upper part of the bore has to be made by "spudding;" the auger or drill being suspended on a rope running up over the pulley at the top of the derrick, and raised and lowered by the skillful manipulation of the end of the rope in the hands of the driller, it having first been carried around the bull wheel, which is kept in motion by the engine. This is continued until the regular string of drilling tools can be used. There are four principal tools, properly so called, used in the process, viz., the centre bit, the auger stem, the jars and the sinker bar. In a well that is being drilled these tools hang in the order named, the centre bit being the lowest. This is a bar of iron, Fig. 26, a few feet long, with a sharp steel cutting edge on the lower end. To this is attached the auger stem, Fig. 27, which is simply a round bar of 4-inch iron from 28 to 40 feet in length. Then come the jars, which have already been described on p. 175. The fourth piece, to