In installing the switchboard at the central office in the general store, the experts from the supply house will attend to all the details of wiring and testing out the circuits in the board. Lines representing the full capacity of the board are brought out in pairs to a connecting strip of maple wood, fastened to the wall at the point of entrance for all outside wires. A cross frame of oak fastened to the roof of the store

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will answer for the terminal tor all outside lines. On this frame the galvanized line wires are fast to insulators. Fig. 1, and the ends of each wire soldered to well insulated copper wire, No. 14 gauge, of the brand often spoken of as Okonite or Kerite wire. This rubber-covered wire enters the building through one duct or hole cut in the wall and hooded over to prevent the entrance of rain or snow.

The insulated wires are connected in proper position upon a fuse frame, which is supplied by the company furnishing the apparatus, and which is illustrated in

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Wire Gauges.

Fig. This frame serves to protect the switchboard should wires become charged with electricity from lightning or a cross with high potential circuits. Each wire is fused with standard mica fuses, which blow at any excess of current over one an pere. Also as an extra preventative each wire fuse terminal is connected to one block of the carbon arrestor, the opposite end of which is grounded. The blocks being separated a small fraction of an inch by a thin slip of silk cloth or mica, do not interfere with the path of the ordinary

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Fig. 2.

current through the fuse, hut should oscillating currents of high arching power reach the fuse, the discharge is carried through the grounded carbon to earth, thus saving the switchboard from harm. The circuit of this device is plainly shown in Fig. 3. All con-

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Fig. 3.

nections made on strips are soldered, with the exception of the fuses which are fastened securely under screw heads and washers.

We will assume that the first line constructed is that of Hyde Bros., whose chair factory we find located at the railroad. As Mr. Chas. C. Hyde, the head of the concern, will also require a telephone, provision is made for connecting an instrument at his house to this line, so that communication may be established between factory and residence without calling central, by ringing upon the line as provided for in the system of ringing suggested for this exchange.

In selecting a line wire the different advantages of both galvanized steel and bare copper wire are to be looked into as regards first cost, maintenance and expense of handling, and it will probably be advisable to procure No. 12 gauge best galvanized iron wire, such

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as is listed at seven cents per pound, subject to discount in mile bundles. It is estimated that one mile of this wire will weigh 164 pounds, and bundles are usually in 1/2 mile coils. Glass insulators of a size suitable for properly running this wire through trees are of the type shown in Fig. 1, the price being 3 cents each by the hundred.

There are two ways of placing the two wires in the trees; first, by fastening separate insulators as far apart as possible in the trees, or else more uniformly, by means of a duplex bracket, which consists of a short, stout stick, a foot in length, bearing an insulator like Fig. 1 at each end. Such a bracket has the disadvantage of damage to both wires should the bracket split and fall away from the tree. In running the line to Hyde Bros., separate insulators are used, fastening same to either side of the main trunk of the trees where possible, in preference to swinging on less substantial branches.

The experienced lineman sent by the supply house will direct all the details of erecting this first line, to the point of entrance at the factory and the residence of Mr. Hyde, at which places the subscribers may feel confident of their ability to commence the work of installing the interior wires and instruments.