t A, Fig; 1. These strips should have sufficient
bend to allow the points to press tightly together. A piece of
beeswax, W, is inserted between the points

[Illustration: Fire Alarm Device]

of the brass strips to keep them apart and to form the insulation.
A binding post, B, is attached to each brass strip on the ends of
the block of wood. The device is fastened to the wall or ceiling,
and wire connections made to the batteries and bells as shown in
the diagram, Fig. 2. When the room becomes a little overheated the
wax will melt and cause the brass strips to spring together, which
will form the circuit and make the bell ring. Each room in the
house may be connected with one of these devices, and all on one
circuit with one bell.

** Home-Made Boy's Car [430]

[Illustration: Boys' Home-Made Auto]

The accompanying cut shows how a boy may construct his own auto
car. The car consists of parts used from a boy's wagon and some
old bicycle parts. The propelling device is made by using the
hanger, with all its parts, from a bicycle. A part of the bicycle
frame is left attached to the hanger and is fastened to the main
board of the car by blocks of wood as shown. The chain of a
bicycle is used to connect the crank hanger sprocket to a small
sprocket fastened in the middle of the rear axle of the car. The
front axle is fastened to a square block of wood, which is pivoted
to the main board. Ropes are attached to the front axle and to the
back part of the main board to be used with the feet in steering
the car. To propel the auto, turn the cranks by taking hold of the
bicycle pedals. --Contributed' by Anders Neilsen, Oakland, Cal.

** Photographs in Relief Easily Made [431]

Relief photographs, although apparently difficult to produce, can
be made by any amateur photographer. The negative is made in the
usual way and,

[Illustration: Reproduced from a Relief Photograph]

when ready for printing, a positive or transparency is made from
it in the same manner as a lantern slide or window transparency,
says the Sketch, London. Use the same size plate as the negative
for the transparency. To make the print in relief place the
positive in the frame first with the film side out and the
negative on top of this with the film side up in the usual manner.
Put in the paper and print. This will require a greater length of
time than with the ordinary negative on account of printing
through double glass and films. In using