150. Handles for Shocking Coils. Fig. 79. Ordinary sheet-tin makes good handles. Cut 2 pieces, each 6 × 4½ in., and connect a stout copper wire to each. This may be done as suggested in Fig. 79, where the tin laps tightly over the bare end of the wire, or by punching 4 or 5 holes through the tin, and weaving the wire back and forth through the holes. Be sure that a tight and permanent connection is made. The wires joined to the handles should be about No. 20, and be 4 or 5 feet long. Roll the tin into a cylinder, so that the connection will be on the inside.
151. Handles for Shocking Coils. Very neat handles may be made from 4-in. lengths of brass tubing that is about ¾ in. in diameter. The wires leading to the coil may be soldered to the handles.
152. Current Regulator for Induction Coils. Fig. 80. If your coil gives too much of a shock with one cell of [App. 3] or [4], you can pull the carbon and zinc partly out of the solution to weaken the shock, or you can use a water regulator. T is an ordinary tin tomato can nearly filled with water, L is a lamp chimney. One wire, A, is fastened to T directly, or by a spring binding-post. The other wire, B, is fastened to a piece of copper, C, which may be raised or lowered inside of L. D is a piece of pasteboard with a small hole in its center.
153. Use. If this apparatus be put anywhere in the primary circuit, the amount of shock can be regulated by raising or lowering C. When C is raised, the current has to pass through a longer column of water than it does when C is near the bottom of L. When C touches T, the current passes easily. If it were not for the chimney, the current would pass to the sides of T.
Fig. 80.