with the upper water, as is frequently the case in drilling for oil. There are three kinds of these tubes. Fig. 50, A, is similar to ordinary gas-pipes, one end being sufficiently widened to serve as a socket-joint, Fig. 50, B. The tubing shown in Fig. 50, C, is contracted on one end so that it can be screwed into the next tube.

Sinking the Tubes.

This is effected as follows: A crib is constructed of wood, cast iron or wrought iron, which also serves for the first tubing of the bore-hole. When made of wood it is either round or hexagonal or octagonal; often a square box suffices.

If made of cast or wrought iron, it is simply a stout pipe. A shaft about 18 feet deep is first dug, in which the crib, Fig. 51, is placed perpendicularly, if possible upon solid rock, so that it is exactly beneath the point of application of the beam. But, if in consequence of water-bearing strata, the condition of the soil is such as to render the digging of a shaft impossible, the crib, when a water-bearing stratum is reached, is placed in position and driven. If in the drilling operation, which now begins, the crib has not reached a more solid stratum, the first tubing is placed in position. For this purpose several lengths of tubing are riveted together and suspended in the bore-hole. The upper end is held by a pair of pipe-clamps projecting sufficiently above them to permit the convenient riveting of the next length of tubing. The pipe-hanger, by means of which the first section of tubing has been lowered into the bore-hole, is now removed and screwed on to the fresh length of tubing. The whole length of tubing is then raised a few inches whilst the clamps are removed from the lower part. When the tubing has been sufficiently lowered, the clamps are reapplied, and the operation of riveting another length of tubing is repeated.

While being lowered the tubing is turned, and this turning should be continued as long as the tubing will move before resorting to driving. Wrought iron tubes when driven must be handled carefully by means of a ring made of wrought iron

from 11⁄2 to 2 inches in height and 3/4 inch thick, or driven with a pipe-dolly. The ring or the dolly is screwed into the lowermost boring rod, and worked at the same rate and in a similar manner to the chisel, due regard being had to the depth at which the driving is being done, as the weight of the boring rods will materially affect the strength of the blow delivered. Cast-iron tubing may be driven hard with a monkey, or forced down by screw-jacks or hydraulic pressure.

If after the boring operation is finished the tubing is to be recovered, it will be necessary to have recourse to cutting in case the lower end of the tubing sits so fast that it is impossible to remove the whole without tearing. For this purpose various tools have been constructed, but only the simplest and most suitable shall here be described.

The stout annular pieces a and b, Fig. 52, are connected by the bolts c, c; d shifts into a corresponding opening of the annular piece b by the raising of the key 7, whereby the cutting wheel g is pressed against the wall of the tubing. The pin s carries the key 1. The upper annular piece a is provided inside with a gas pipe thread for 2-inch tubing, but the key / with a thread for correspondingly slighter rods. In cutting, the rods are screwed in with a female screw, the tubing being turned at the same time until cut through.

The withdrawal of the tubing is best effected by wedging a riveting clamp in the upper end of the tubing and lifting the latter by it. If the tubing sticks fast the lower portion is first cut off and lifting is then continued. If still unsuccessful, stout boring rods are brought into requisition. The lower end of the rods is provided with a screw with left-handed thread. A wooden cylinder, Fig. 53, wider in the centre, is stuck upon the lower round end of the rods, and the latter screwed in the female screw s inserted in the wood. If now the wooden cylinder reaches a certain point in the tubing, the rods are fastened and coarse sand and gravel poured into the tubing. On raising the rods the conical cylinder is firmly squeezed against the tubing, and in this manner the latter is withdrawn without damage.

In case the tubing does not stick too fast, its withdrawal may also be effected by means of the instrument shown in Fig. 54. The two legs a a are connected below with the hooks b b, and above with the boring rods. The wedge d is provided on the upper end with jars which can be brought into activity by means of the sludger cable. The legs are of sufficient length for the jars to find room between them. After inserting the instrument in the tubing to be raised the wedge is keyed by means of a wedge and the jars.

In the United States lining tubes are cut out as follows: An expanding cutter-head, in which the circular cutter-heads are first tightened, is lowered into the bore-hole and then put into action by turning the boring rods at the surface.

Among the auxiliary tools may also be mentioned the instruments used to withdraw broken or defective tools. They are of all kinds and devices, from the delicate grap designed to pick up a small piece of valve leather, or a broken sucker-rod rivet from the pump chamber, to the ponderous string of pole tools containing tons of iron, which, at a depth of 1,500 feet or more, can unscrew a set of stuck tools, and bring them up piece by piece, or cut a thread upon the broken end of a sinker bar, or an auger stem, so that it can be screwed fast to and loosened by the use of "whiskey jacks" at the surface.

In conclusion we furnish to of the drilling operation, which through which the drill passes. three general heads: 1. What may be termed the surface drift, composed of alluvial soil, beds of gravel, sand of loose texture. This division may have a depth of only a few feet in some places; in others, in the valleys, it may be two or three hundred feet thick. 2. The water-bearing rocks, at the bottom of which, where the drill has reached this point, a "seedbag" packing is placed to prevent the inflow of water into the well. 3. The rocky strata in which little or no water is found. These comprise one thousand or fifteen hundred feet of the whole depth of the well. A well was dug at Titusville through

our readers a diagram, Fig. 55, exhibits also the different strata. These may be classified under