in length and of the same size and material as the line wire n n. On straight lines the line wires are placed on the inner sides of the insulators, excepting the two wires next to the pole, which are placed

n

n

FIG. 77.-Method of Tying the Line Wire to its Insulator

FIG. 78.—Position of the Line Wires on the Insulators in Straight Lines

a

FIG. 79.-Position of the Line Wires on the Insulators at Curves

FIG. 80.-The Standard Western Union Joint for Connecting Iron Wires

outside to afford greater clearance of the pole. On curves, the line wires are placed so that the strain draws them against the insulators. These two cases are shown respectively in Figs. 78 and 79. Joints in iron wires are made as in Fig. 80, which

shows what is known as the "Standard Western Union" joint. Joints in copper wires are made with McIntire copper sleeves, Fig. 81, each hole in

FIG. 81. McIntire Sleeve for Connecting Copper Wires

the sleeve being no more than 0.01 inch larger than the wire with which it is used. The ends of the copper wires to be joined are inserted in the respective halves of the sleeve from opposite ends, so that each wire projects one-quarter inch beyond

FIG. 82.-Pliers for Use in Connection with McIntire Sleeves

the sleeve. The ends are then turned over, and by means of McIntire pliers, Fig. 82, the sleeve and wire are twisted as in Fig. 83.

Dead-Ending a copper line wire on its last insu

FIG. 83.-Copper Wire Joint as Made by a McIntire Sleeve

lator for the purpose of connecting it to a cable or to a station instrument is done as in Fig. 84, the line wire being first slipped through a McIn

tire half-length sleeve n, then wrapped once around the insulator, and finally run back through the sleeve, which is then given one and one-half turns.

Transposing Line Wires.-Telephone instruments are so sensitive that cur

-n

rents induced in the line wires from neighboring circuits produce in the telephones disturbing noises. commonly termed "cross talk," unless care is taken to prevent them. To overcome disturbances of this nature, which are especially troublesome in the vicinity of electric-light and power wires, both lines of a telephone circuit must be metallic and balanced with respect to adjacent lines so that the induction from them is neutralized; this balancing is done by transposing the line wires of each telephone circuit on a pole at regular intervals along the line.

FIG. 84.Method of Dead-ending a Wire

The method of making the transpositions is shown in Fig. 85. Transposition pins and insulators and McIntire sleeves are employed. Supposing the line wires m m and n n of a complete metallic circuit are to be transposed, these wires are cut and the two ends of each are dead-ended on the transposition insulator corresponding to that line, the upper groove of the insulator being used for one end and the lower groove for the other end. The four terminals of the two line wires are then

n

cross-connected by the sleeves r and s so that instead of m m and n n being continuous, m n and nm are continuous.

Four complete metallic circuits A, B, C, and D, Fig. 86, have thus been transposed at a, b, c, d, etc. Considering, for example, the circuits A and B, of which m and n are the conductors of the former and s and r those of the latter, it is obvious

m

W

'S

FIG. 85.-Method of Transposing Line Wires

that if a current in n induces a current in s, the current in the other wire m of circuit A will induce ins a current equal in value and opposite in direction to the first induced current if the transposition a be made. The two induced currents will, therefore, neutralize each other, removing the cause of the disturbances, and in the same manner the other transpositions shown will prevent inductive disturbances in the other parts of

m

n

Q

D

the circuit. In circuit C the wires should be transposed at about every tenth pole, and in the other circuits transpositions should be made relatively as shown.

In addition to the desirability of thus having both wires of a complete metallic telephone circuit subject to the same amount of inductance, they should also have substantially the same ohmic

x

d

x

FIG. 86.-Relative Locations of Transpositions in Four Adjacent Circuits

resistance, the same insulation resistance, and the same electrostatic capacity. Aside from the transpositions, both wires should, therefore, be of the same material and of equal lengths, and should be insulated in the same manner on the same cross-arms or in the same cable, and should always be adjacent to each other.

Drop Wires.-The drop wires running from the line to the premises of the telephone user may