When joining two ends of wire together, never make loops as shown in [Fig. 12] A. This construction gives poor contact, for the wire loops will wear and finally break apart. Moreover, the rust that forms between the loops will often cause an open circuit and one difficult to locate. Care must be taken to make all splices secure and with perfect contact of wires, and the only manner in which this can be done is to pass the ends of wires together for three or four inches, as shown in [Fig. 12] B.
Grasp one wire with a pair of plyers, and with the fingers start the coil or twist, then with another pair of plyers finish the wrapping evenly and snugly. Treat the other end in a similar manner, and as a result you will have the splice pictured in [Fig. 12] B, the many wraps insuring perfect contact. This same method is to be employed for inside wires, and after the wrap is made heat the joint and touch it with soldering solution. The solder will run in between the coils and permanently unite the joint. The bare wires should then be covered with adhesive tape.
Avoid sharp turns and angles in lines, and where it is not possible to arrange them otherwise it would be well to put in a curved loop, as shown at [Fig. 13]. A represents a pole, B B the line, and C the quarter-circular loop let in to avoid the sharp turn about the insulator. The current will pass around the angle as well as through the loop, but a galvanometer test would show that the greater current passed through the loop and avoided the sharp turn.
“Grounds”
In the [chapter] on wireless telegraphy several good “grounds” were described, any one of which would be admirably adapted to telegraph or telephone circuits. In [Figs. 14], [15], and [16] are illustrated three other “grounds” that can easily be made from inexpensive material. The first one, [Fig. 14], is an ordinary tin pan with the wire soldered to the middle of the bottom. The wire must be soldered to be of use, as the pan would soon rust around a simple hole and make the “ground” a high-resistance one. If the pan is buried deep enough in the earth, and bottom up, it will last for several years, or so long as the air does not get at it to induce corrosion.
The star-shaped “ground” is cut from a piece of sheet zinc, copper, or brass, and is about twelve inches in diameter. The wire is soldered to the middle of it, and it is buried four feet deep, lying flat at the bottom of the hole.