The same form of fuse may be made from a strip of mica about two and one-half inches long and one-half an inch wide.
A strip of thin sheet-copper is bent around the ends of the mica strip.
A piece of fuse wire is stretched between the two copper contacts and fastened to each with a drop of solder. Fuse wire of any desired ampere-carrying capacity can be obtained from most electrical supply houses.
Such a fuse is held in a mounting as shown by D. The contacts are made from sheet-copper or brass. They should spring together very tightly, so as to make perfect contact with the copper ends on the mica strip.
Lightning-Arresters
Lightning-arresters are used to protect all wires which run into a building from outdoors, especially telegraph or telephone wires, so that static electricity due to lightning will not damage the instruments.
Lightning-arresters may be constructed in many ways and of different materials, but there are only two types for which the average experimenter will have any use.
Fig. 99.—Lightning-Arrester and Ground-Wire Switch.
The arrester shown in Figure 99 is the type known as "lightning-arrester and ground-wire switch." It is used principally on telegraph lines.