ent as shown and securely fastened to the cardboard end of
the coil. The armature is made from a soft piece of iron, about
3/16 in. in diameter and 1/16 in. thick, which is soldered to the
end of the vibrator directly opposite the end of the core. A small
screw is fitted in the end of the support, C, for adjustment,
which should be tipped with platinum and also a small piece of
platinum placed where the screw will touch the vibrator, B.

One of the primary wires is connected to the screw support. The
vibrator, is connected to a flash lamp battery, D. The other
primary wire is connected to a switch, S, which in turn is
connected to the other terminal of the battery. The switch, S, may
be made from a 3/8-in. cork with the wires put through about 3/16
in. apart and allow them to project about 1/2 in. The plate E is
cut about 1/2 in. square from a piece of copper and is fastened to
the heel of one shoe and connected with a wire from the secondary
coil which must be concealed inside of the trouser leg. The other
secondary wire is connected through the coat sleeve to a finger
ring, F. The vibrator screw must be properly adjusted. When the
vibrator is not working the armature should be about 1/16 in. from
the core and directly opposite.

The coil when complete will be about 2-1/2 in. long and 1 in. in
diameter. The coil can be placed in an old box that has been used
for talcum powder or shaving stick. The space around the coil in
the box can be filled with paper to keep it tight.

The coil and battery are carried in the pockets and the cork
button put in the outside coat pocket, where it can be pressed
without attracting attention.

** Experiment with Heat [134]

[Illustration: Heat Experiment]

Place a small piece of paper, lighted, in an ordinary water glass.
While the paper is burning turn the glass over and set into a
saucer previously filled with water. The water will rapidly rise
in the glass, as shown in the sketch.

** How to Attach a Combination Trunk Lock [134]

[Illustration: Trunk Lock]

A small combination lock for chests can be purchased for a small
sum of money and attached to a trunk cover after first removing
the old lock as shown in Fig. 1. It is necessary to add 1/2-in. to
the thickness of the trunk lid or cover. This may be done by
placing a brass plate 1/8-in. thick on the outside and a board
3/8-in. thick on the inside. The lock, brass plate, board and
trunk cover are all securely riv