A surgeon’s probe, designed to indicate by the closing of an electric
circuit the presence of a bullet or metallic body in the body of a
patient.

Two insulated wires are carried to the end where their ends are exposed,
still insulated from each other. In probing a wound for a bullet if the
two ends touch it the circuit is closed and a bell rings. If a bone is
touched no such effect is produced. The wires are in circuit with an
electric bell and battery.