Fig. 82.
156. Interrupter. Fig. 82. The nails in this apparatus are placed in a circle about 4 in. in diameter. They are electrically connected to each other by a bare copper wire, which is wound around each nail several times, and then led out to one of the binding-posts. In the center of the circle is a nail, or screw, which is connected by a wire to the other binding-post, care being taken not to allow the two wires to touch each other. Around the central screw is wound one end of a stout wire, the other end of which reaches out from the screw far enough to touch the nails. When this stout wire touches any nail, a current entering one binding-post can pass through nails, screw, etc., and out at the other binding-post. When the end of the stout wire is between two nails, the current cannot flow. By placing the finger against this stout wire and turning it around rapidly, the current can be interrupted as desired. The base should be about 5 × 6 × ⅞ in.
157. Interrupter. Wind the end of the wire from one pole of the battery around the handle of the file. Scrape the other wire along the rough file. As it jumps from one ridge to another the current will be rapidly interrupted.
158. Interrupter. Hold the end of the wire from one pole of a battery upon a saw-blade. Draw the other wire along over the teeth of the saw. As the wire jumps from one tooth to the next the current will be broken.
159. Automatic Interrupter. An ordinary electric bell, or buzzer, may be used as an interrupter. Every time the vibrating armature swings, the circuit is opened. The combination of a battery, induction coil, and electric bell makes a very good outfit for medical purposes. The automatic interrupter used on [App. 100] should be studied.