diagram and filing a knob on each end, at opposite sides to each
other, on which to hook the blade. For the blade an old
talking-machine

[Illustration: Hacksaw Frame and Blade]

spring or a clock spring will do nicely. Heat the spring enough to
take some of the temper out of it, in order to drill the holes in
the ends, as shown, and file in the teeth. Make the blade 12 in.
long, with 10 teeth to the inch. A and B show how the blade fits
on the frame. -Contributed by Willard J. Hays, Summitville, Ohio.



** How to Make a Cannon [42]

A cannon like the one in the cut may be made from a piece of 1-in.
hydraulic pipe, A, with a steel sleeve, B, and a long thread plug,
C. Be sure to get hydraulic pipe, or double extra heavy, as it is
sometimes called, as common gas pipe is entirely too light for
this purpose. Don't have the pipe too long or the cannon will not
make as much

[Illustration: Toy Cannon]

noise. Seven or eight inches is about the right length for a 1-in.
bore. Screw the plug and pipe up tightly and then drill a 1/16-in.
fuse hole at D.

If desired the cannon may be mounted on a block of wood, F, by