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I I 2 THE BOY ELECTRICIAN

The simplest possible fuse consists merely of a small" piece
of lead wire or a strip of thick tinfoil held between two
binding-posts mounted upon a wooden block.

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 ob-
tained 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-Arreatera

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 con-
structed in many ways and of dif-
ferent materials, but there are only
two types for which the average
FIG. 99. Lightning_Anester experimenter will have. any use.

and Ground-“fire switch, The arrester shown 1n Flgure 99

 

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