FIGS. 62, 63. INCANDESCENT WIRE FUSE. ABEL'S PATENT.

FIG 64. VON EBNER'S FRICTIONAL ELECTRIC MACHINE FOR

EXPLODING ELECTRIC FUSES OR DETONATORS.

Bi-telephone.

A pair of telephones arranged with a curved connecting arm or spring, so

that they can be simultaneously applied to both ears. They are

self-retaining, staying in position without the use of the hands.