The Boy Mechanic: Volume 1 | Page 2

steam is accomplished by means of slots, I,

sawed into the fronts of the cylinders at about 1/8 in. above the lowest
position of the piston's top at the end of the stroke, at which position of
the piston the valve rod drops into the cutout portion of the cam and
allows the valve to seat.
All the work on this engine, save turning the pistons, which was done
in a machine shop for a small sum, and making the flywheel, this being
taken from an old dismantled model, was accomplished with a hacksaw,
bench drill, carborundum wheel, files, taps and dies. The base, Q, is
made of a heavy piece of brass.
The action is smooth and the speed high. Steam is supplied by a sheet
brass boiler of about 3 pt. capacity, heated with a Bunsen burner.
--Contributed by Harry F. Lowe, Washington, D. C.

** Magic Spirit Hand [2]
The magic hand made of wax is given to the audience for examination,
also a board which is suspended by four pieces of common
picture-frame wire. The hand is placed upon the board and answers, by
rapping, any question asked by members of the audience. The hand and
the board may be examined at any time and yet the rapping can be
continued, though surrounded by the audience.
The Magic Wand, London, gives the secret of this spirit hand as
follows: The hand is prepared by concealing in the wrist a few soft iron
plates, the wrist being afterwards bound with black velvet as shown in
Fig. 1. The board is hollow, the top being made of thin veneer (Fig. 2).
A small magnet, A, is connected to a small flat pocket lamp battery, B.
The board is suspended by four lengths of picture-frame wire one of
which, E, is
[Illustration: Wax Hand on Board and Electrical Connections]
connected to the battery and another, D, to the magnet. The other wires,
F and G, are only holding wires. All the wires are fastened to a small
ornamental switch, H, which is fitted with a connecting plug at the top.

The plug can be taken out or put in as desired.
The top of the board must be made to open or slide off so that when the
battery is exhausted a new one can be installed. Everything must be
firmly fixed to the board and the hollow space filled in with wax, which
will make the board sound solid when tapped.
In presenting the trick, the performer gives the hand and board with
wires and switch for examination, keeping the plug concealed in his
right hand. When receiving the board back, the plug is secretly pushed
into the switch, which is held in the right hand. The hand is then placed
on the board over the magnet. When the performer wishes the hand to
move he pushes the plug in, which turns on the current and causes the
magnet to attract the iron in the wrist, and will, therefore, make the
hand rap. The switch can be made similar to an ordinary push button so
the rapping may be easily controlled without detection by the audience.

** Making Skis and Toboggans [3]
During the winter months everyone is thinking of skating, coasting or
ski running and jumping. Those too timid to run down a hill standing
upright on skis must take their pleasure in coasting or skating.
The ordinary ski can be made into a coasting ski-toboggan by joining
two pairs together with bars without injury to their use for running and
jumping. The ordinary factory-made skis cost from $2.50 per pair up,
but any boy can make an excellent pair far 50 cents.
In making a pair of skis, select two strips of Norway pine free from
knots, 1 in. thick, 4 in. wide and 7 or 8 ft. long. Try to procure as fine
and straight a grain as possible. The pieces are dressed thin at both ends
leaving about 1 ft. in the center the full thickness of 1 in., and gradually
thinning to a scant 1/2 in. at the ends. One end of each piece is tapered
to a point beginning 12 in. from the end. A groove is cut on the under
side, about 1/4 in. wide and 1/8 in. deep, and running almost the full
length of the ski. This will make it track straight and tends to prevent

side slipping. The shape of each piece for a ski, as it appears before
bending, is shown in Fig. 1.
The pointed end of each piece is placed in boiling water for at least 1
hour, after which the pieces are ready for bending. The bend is made on
an ordinary stepladder. The pointed ends are stuck under the back of
one step and