Before winding the secondary coil the primary coil should be covered with two layers of thick note-paper, which previously has been well soaked in paraffin. Any unevenness should be smoothed over with additional paraffin, so that the windings of the secondary coil may be regular and level. The joints at the ends should be completely filled with paraffin to prevent short circuits between primary and secondary coils.

The secondary coil consists of 15 layers of No. 36 cotton-covered magnet wire. The end is carried through the hole D, leaving about 8" for connections. It is temporarily fastened with a plug. Owing to the fineness of the wire and the liability of breaking, the ends are often of larger wire, with soldered connection, well covered with cotton thread and waxed. The secondary is wound in the same direction as the primary coil, each layer being coated with shellac, as previously described. The wire should be carefully watched during the winding to locate breaks or splices. If either are found, twisted joints should be made and well covered with fine cotton thread and wax. Each layer should end one turn further from the end than the one under it, the remaining space being filled with paraffin. If the last layer is likely to be rather uneven, a layer of note-paper over the next to the last layer, coated with shellac, will allow the last layer to be wound evenly. This should be shellacked, the end, with spare wire for connections, being carried through the hole F. A covering of black velvet or bookbinders' leather will give the coil a more finished appearance, as well as protect the coil from being damaged by use. When the winding is completed, the core is then placed in position and strongly fastened with glue. It should fit very firmly and be centered so that the regulator may be pushed in and out without touching it.

Five binding posts are fitted to the base, as shown in Fig. 1. Holes should then be bored in the base to receive the wires from the primary and secondary coils. Six brass-headed upholstering nails are driven into the under side of the base to support it and prevent the wiring underneath from being broken.

The contact-breaker consists of a piece of thin spring steel 21/2" long and 3/16" or 1/4" wide, on one end of which is soldered a piece of soft iron 3/8•" square and 1/8 thick, which forms the armature. The other end is fastened in a slot in the top of a brass or iron post 141/4" high, so placed as to bring the armature opposite the end of the core. The post can easily be made of a brass bolt, the slot being cut with a key-maker's file or hacksaw. The end of the spring is then placed in the slot and the two sides hammered gently until firmly closed onto the spring. "With one nut above the base and one on the under side, the post can then be firmly fastened in any desired position. Another post with a regulating contact-screw in the top is placed 1" nearer the coil, but outside the spring. A screw-hook may be substituted for the contact-screw and post to save work. It should be about 21/2" long, and screwed through the base far enough to allow the wire connections to be made.

When all the parts are completed, they should be fastened to the base, the armature on the contact-breaker not quite touching the core, and having an outward play of about 1/8". The wires from the primary and secondary coils are carried under the base to make the connections shown in Fig. 1, as follows : The outside end of the primary coil is carried to the binding-post P; the inside end of the primary coil to the post carrying the spring and armature. The post with the contact-screw is connected to the binding-post N, and also connected to the binding-post Tt. A splice is made on the wire from the inside of the primary coil and run to the binding-post Ts.

The inside end of the secondary coil is connected to the post Tt, and the outside end to the post Tp. The wire for these connections should be heavier than the coil wire, say No. 18 annunciator wire. The wire plan, in Fig. 1 is simply to show the proper connections. The wires are carried as direct as possible. The battery is connected to the posts P and N with No. 18 annunciator wire. Two Leclanche cells connected in series will probably furnish all the current desired. Handles for shocking are made from pieces of thick brass tubing 4" long and 3/4" diameter. Wooden handles are fitted to one end. Flexible wire cord, such as is used on incandescent drop-lamps, makes good connecting wire from coil to handles. It should be soldered to the tubing, and at the outer end a coating of solder will prevent breakage from use in changing terminals. Connecting the wires from the handles to the posts Tt and Tp, the shock will be that given by the primary coil only; posts Tt and Ts give secondary-coil only ; while posts Ts and Tp will give both primary and secondary. The first connection will be found the weakest, the second much stronger, and the last quite powerful. With the regulator out, each connection will be at its full strength, but by sliding in the regulator, they are reduced. In first testing the coil, do not take the full strength, but work up to what you can stand with comfort. Electricity, like anything else, is to be taken in moderation. Some adjusting of armature spring and contact-screw will probably be necessary before the current-breaker will work correctly.