A fuse for igniting an explosive by electricity. There are two kinds. In
one a thin wire unites the ends of the two conducting wires as they
enter the case of the fuse. The larger wires are secured to the case, so
that no strain comes on the fine wire. On passing a current of
sufficient strength the small wire is heated. In use the fuse is bedded
in powder, which again may be surrounded by fulminating powder, all
contained in a copper or other metallic case. Such a detonator is used
for exploding guncotton and other high explosives.

The other kind of fuse is similar, but has no thin connecting wire. The
ends of the conductors are brought nearer together without touching. In
use a static discharge is produced across from end to end of the
conductors, igniting a proper explosive placed there as in the other
case.

The first kind of fuse is generally operated by a battery or small
mechanical generator–the latter by a spark coil, frictional or
influence machine or by a Leyden jar.