ng careful that none of the fastening
nails made an electrical connection between the zinc plate and the
tin pan.

This apparatus was placed on the floor of the warehouse where it
was plainly visible from a window in the shop where we worked and
a wire was run from the pan and another from the zinc plate
through the intervening yard and into the shop. A good sized
induction coil was through connected with these wires and about
six dry batteries were used to run the induction coil whenever a
push button was manipulated.

It is quite evident that when a rat put its two fore feet on the
edge of the pan in order to eat the mush which it contained, that
an electrical connection would be made through the body of the
rat, and when we pushed the button up in the shop the rat would be
thrown

[Illustration: Electric Rat Trap]

2 or 3 ft. in the air and let out a terrific squeak. The
arrangement proved quite too effective, for after a week the rats
all departed and the boys all regretted that their fun was at an
end.
--Contributed by John D. Adams, Phoenix, Ariz.

** How to Make a Simple Fire Alarm [359]

A fire alarm which is both inexpensive and simple in construction
is shown in the illustration. Its parts are as follows:

A, small piece of wood; B, block of wood nailed to A; S S. two
pieces of sheet brass about 1/4 in. wide, bent into a hook at each
end; P, P, binding-posts fastening the springs S S, to block B, so
that they come in contact at C. W is a piece of wax crayon just
long enough to break the contact at C when inserted as shown in
the illustration.

When these parts have been put together in the manner described,
connect the device in circuit with an electric bell, and place it
behind a stove.

[Illustration: Simple Fire Alarm]

When the stove becomes too hot the wax will melt at the ends,
allowing the springs to contact at C, and the alarm bell will
ring.
--Contributed by J. R. Comstock, Mechanicsburg, Pa.

** To Build a Merry-Go-Round [359]

This is a very simple device, but one that will afford any amount
of amusement. The center post rests in an auger hole bored in an
old stump or in a post set in the ground. The stump makes the best
support. The center pole should be 10 ft. high. An old wheel is
mounted at the top of the pole, and the pole works in the wheel as
an axle, says the American Boy. The wheel is anchored out by
several guy

[Illustration: Home-Made Merry-Go-Round]

wire