Fig. 199.—Various Types of Aerials.
The aerial should be at least thirty feet high.
The wire should not be smaller than No. 14 B. & S.
The masts which support the aerial should be of wood and provided with pulleys so that the wires may be lowered any time it may be necessary. The mast should be thoroughly braced with stays or guys so as to counteract the strain of the aerial.
The aerial should not be hoisted up perfectly tight, but should be allowed to hang somewhat loose, as it will then put less strain on the ropes and poles that support it.
When an aerial is to be fastened in a tree, it is best to attach it to a pole placed in the top of the tree, so that it will come well above any possible interference from the branches.
The wires leading from the aerial to the instruments should be very carefully insulated throughout their length. This part of the aerial is called the "rat-tail" or lead-in.
The illustrations in Figure 199 show the proper place to attach the “lead-in" form of aerial. The wires should gradually converge.
Fig. 200.—A Ground Clamp for Pipes.