The old pole, which has been badly decayed at the ground line, is sawed off at this point, and then moved to one side without any interference with the overhead wires. By means of an axe and a draw-knife the butt is slightly tapered to fit inside of the upper end of the socket. Only three men are needed to do the entire work. While one man is shaping the pole, two other men at first remove the stump or decayed portion of the old pole, and then make an excavation of sufficient size to allow the pole socket to be easily inserted up to the point where it has a constriction. The bottom of the socket is then filled with either dry earth, shale or concrete to within one foot of the ground surface. This inner filling is firmly tamped. A thick grout is then prepared and poured into the socket to a point above the constricted ring. Everything is now ready to receive the pole, which is raised with a jack, moved into position over the socket and then allowed to enter the same. As it does so, it squeezes the grout up and around the pole, filling all of the space between the pole and the socket up to its upper edge. The pole is made fast and held plumb while the grout hardens. In some instances a shell of concrete three or four inches thick is rammed about the socket to about a depth of two feet below ground surface.

The entire cost of repairing an old pole with a socket of this character does not exceed $10 per pole of large size, and $6.50 for a small pole,

which is very low, compared with the total cost of placing a new pole. The pole is entirely protected at its weak point and is made fully as strong, even stronger than when it was originally set. There is no disturbance of the overhead wiring or crossarms at all and the work of restoration can be rapidly done.

Conduit Construction.—It has become the practice in recent years to run telephone wires in underground conduits through the business districts of cities of any importance. The initial planning includes the location of the various ducts and manholes, determining the best methods of laying and making all provision possible to take care of any possible expansion of the business by laying ducts enough in the first place to avoid tearing up the streets again at some future time to lay more conduits. The essential requirements to be considered in selecting conduit are: first, to select durable material that will be proof against decay, corrosion from dry rot, dampness, gases or other agencies of deterioration. Second, the

material should have high tensile strength, high resistance against shearing and to crushing. The greatest degree of resistance should be in the vertical plane, because ground settling produces vertical strains, and any fractures due to these will not only impair the alignment of the ducts and interfere with the drawing in or out of the cables, but will also interfere with proper drainage. It is preferable to lay the ducts as straight as pos

FIG. 97h.-Forms of Conduit Generally Used. sible between manholes, but sometimes curves are unavoidable, and it is necessary to make these of sufficiently large radius so as not to cause abrasion of the cable sheath when drawing in.

Conduits should contain no chemical substances that are apt to act on the cable sheath, and the structure should be of insulating material and moisture proof. The cables must in all cases be adequately protected from dampness and water and should be insulated from the ground. It is important to form all bends of curved sections if the nature of the conduit permits rather than joining short, straight pieces, as is frequently done in describing curves of large radius.

Conduits are of many types and materials, the cheapest form consisting of creosoted wooden tubes generally known as pump logs. These are made in eight-foot lengths and have a bore of three inches. They are 41⁄2 inches square and are provided with tenon joints 11⁄2 inches long to secure alignment. Conduit of this nature is shown at Fig. 97h, A. Conduits of clay or terracotta, as shown at Fig. 97h, B, are also widely used. These have hard, vitrified surfaces, which are impervious to moisture. These are made in single or multiple duct forms, and for telephone conduits some ducts have a round opening, while others have a square bore about 4 inches in diameter. Wood conduits are generally laid in a trench, the bottom of which is graded to a gradual slope toward both manholes from some intermediate point or with a continuous slope from one manhole to the others. A creosoted plank 2 inches in diameter serves as a foundation on which the wooden ducts are laid side by side

in different layers to the number required. Endeavor is made to have the joints of separate conduits at different points in order to strengthen the When the ducts are laid, the top is covered with another creosoted plank, and the trench is filled in.

structure.

In laying vitrified clay conduit, a concrete foundation is laid in the bottom of the trench, and the ducts are then laid in with cement and the sides of the trench filled up to each duct level as each layer is laid. When the conduit is all laid and all layers are completed the top is covered with 4 inches of concrete. A good mixture for this purpose is composed of 1 part Portland cement, 2 parts clean, sharp sand and 5 parts broken stone or screened gravel.

The standard underground cable used in cities is shown in Fig. 97i, and contains about 100 wires of approximately No. 19 B. & S. gauge. These