About 1 in. behind the coils is fastened a small block of wood, the top of which is just even with the top of the nails in the coils. A piece of tin, cut in the shape of the letter T, is fastened with two screws to the top of this block, and the end bent slightly so as to clear the top of the nails about 1/32 in.
The key lever is cut from a thin piece of wood, in the shape shown in the sketch, and pivoted in a slotted block which is used as a base for the key. A piece of bare copper wire is fastened along the under side of the key, as shown by the dotted lines. A rubber band, passing over the end of the key and attached to the base with a tack, acts as a spring to keep the key open. A small piece of tin is fastened to the base under the knob of the key. This is for making the contact between the copper on the key and the wires from the coils, when the key is pushed down.
Contributed by W. H. Lynas.
Protecting Sleeves
Bicycle trousers-guards make excellent sleeve bands when the cuffs are turned back and rolled above the elbows.
Imitation Arms and Armor—Part VII
