sufficiently high to permit the use of the path `n. The anchor guy s is fastened to a about 3 inches below m, and both s and m are held in place by staples. The guy stub should be strengthened by 2 logs cand e as shown.

Trees are sometimes convenient for anchors, but when thus used should be protected with lagging of boards or staves placed around the tree where the guy cable is wrapped. No limbs under 5 inches in diameter should ever be used for anchors; in any case the trunk of the

tree is preferable.

મેનોને મોજે

Pole

braces are

used where it is im

practicable to use a

guy. These

are

placed so as to halve

FIG. 71. Method of Bracing a
Telephone Pole

the acute or inside angle formed by the poles. For example, in Fig. 68 the brace r, consisting of a pole similar to the telephone pole, is placed as shown and serves the same purpose as the guy cable v in counterbalancing the side strain upon h. Fig. 71 shows the method of installing a brace. It is bolted at the lower end to an anchor log c buried 6 feet below the surface, and the other end is secured to the telephone pole by means of 2 nails

driven through the 2 poles and by No. 6 iron wire a wrapped 3 times around the poles and held in place on the brace by a 5-inch fetter drive screw.

Pole Brackets.-These may be used in place of cross-arms for supporting telephone wires when the pole is not to contain over 6 wires. In this case no gains need be cut on the pole, as the brackets are

B

FIG. 72.-Pole Brackets

screwed directly to the sides of the poles. Wooden brackets, A, Fig. 72, are generally used where the pole is to carry 1 or 2 wires, and iron brackets, B, Fig. 72, for more than 2 wires. Where more than I bracket is needed, they are placed on opposite sides of the pole so that there is the same number of wires on both sides.

The lineman climbs the pole after it is set, by means of spurs strapped to his legs, and fastens the brackets in place with drive screws.

Cross-Arms. If cross-arms are to be used they should be bolted in the gains cut for them on the poles, after the poles are in position. The lineman carries with him up the pole a pulley and a coil of rope. The pulley he fastens to the top of the pole and then passes the rope through it, allow

ing both ends to reach the ground. His assistant ties the cross-arm to one end of the rope and by pulling the other end raises the cross-arm to the lineman, who fastens it in place as shown in Fig. 65 at a, using a 9-inch machine bolt, nut, and square washers. Two cross-arm braces c and e, Fig. 65, of 4-inch galvanized steel, each 28 inches in length and 1 inch in width, are also attached to each cross-arm by a 4-inch carriage bolt r, and together are secured to the pole by one 3-inch fetter drive screw S.

All cross-arms should be made of thoroughly seasoned straight-grained yellow pine. The wood should be solid, free from cracks, knots, sap wood, and dry rot. The principal dimensions are given in the following table. The finished measurements are 3 by 44 inches. The pin holes should be such as to afford a driving fit for the pins, and the central hole for the ğ-inch machine bolt should be 1-inch in diameter. Cross-arms should be rounded at the top to shed water, and well painted with lead and oil before being placed in position.

Cross-Arm Pins.-These are made of locust, and in straight-line construction have the form and

dimensions shown in Fig. 73. The shank b fits into the hole in the cross-arm, and is held by a 6-penny wire nail driven through the side of the arm; the flange d prevents water from entering

the hole. The screw threads at

a are cut to fit the threads of a glass insulator which screws on the pin. The pin, Fig. 73, is used in supporting but one line and is called a line pin. There is another kind called a transposition pin which is used for supporting 2 lines; this pin differs from that shown only in having the thread cut 3-inch longer.

Insulators.-Insulators for the cross-arm pins are made of glass in two forms: line insulators to fit line pins, and transposition insulators to fit transposition pins. One of the former kind is shown at A, Fig. 74, and one of the latter at B, Fig. 74. It will be noted. the simple insulator has but one groove for wire and is made in one piece, whereas the transposition insulator is made in two pieces in each of which there is a groove for a wire. In placing a transposition insulator on a pin the lower glass is first screwed on so that about 1 inch of the thread of the pin projects through the hole. The upper

32

glass is then screwed down tightly on the lower half.

Telephone Line Wire.-Galvanized iron wire and copper wire are both used for telephone-line conductors. Iron is stronger and cheaper than copper, but offers nearly six times as much resistance to a current of electricity. Iron line wire is always galvanized to prevent it from rusting, but even the best galvanizing fails to prevent corrosion entirely,

in consequence of which iron wire will usually serve less than half the time of copper wire. On the other hand, iron wire costs but 3 cents per pound, whereas copper wire costs about 15 cents per pound. For a private line it is usual practice to use No. 12 galvanized iron wire; for bridging lines not over 25 miles in length, No. 12 galvanized iron wire; and for longer lines No. 10 or No. 8 galvanized iron wire. When copper wire is employed, sizes from No. 8 to No. 14 are used; the No. 12,