right
surface of the tin. If difficulty is found in obtaining a circular
piece of glass, the bottom may be made square and square glass
used. Use plain, clear glass; not magnifying glass. To picnic
parties the water telescope is of great amusement, revealing
numerous odd sights in the water which many have never seen
before.

** How to Rid Your Yard of Cats [411]

The following is a description of a device I built at my home in
Brooklyn, which not only gave us relief from the

[Illustration: Electric Apparatus for Driving Away Cats]

nightly feline concerts, but also furnished much amusement to my
friends.

I first ran two bare copper wires along the top of the fence about
1 in. apart, fastening them down with small staples, care being
taken that they did not touch. To the ends of these wires I
fastened ordinary insulated bell wire, running them to the house
and connecting them to the upper binding-posts of an induction
coil; I then ran a wire from the lower binding-post of my coil
through the batteries back to the other lower binding-post of
coil, breaking the circuit by putting in an ordinary switch. The
more batteries used, the stronger the current. The switch should
always be left open, as it uses up the current very rapidly.

When "tabby" is well on the wires I close the switch and she goes
the length of the fence in bounds, often coming back to see what
the trouble is, thus receiving another shock.
--Contributed by Charles L. Pultz.

** Substitute for a Drill Bit [411]

A gouge may be used as a substitute bit if a proper sized bit is
not at hand. The gouge can be placed in the brace the same as a
bit.

** Drying Films [412]

The drying of photographic film in full lengths without scratching
or curling is quite difficult. Various devices are used to keep
the film straight, and

[Illustration: Pins Keep the Film Straight]

push pins or thumb tacks are supplied with almost all of them. The
illustration shows a simple and inexpensive device constructed of
common wood clothespins without any metal pins to come in contact
with the film and cause rust streaks. A pair of pins are fastened
at each end of the film by pushing one pin over the other which in
turn is clamped on the film. A string tied to the heads of one
pair of pins provides a way to hang the whole on a nail. The lower
pair of pins makes a weight to keep the film straight.
--Contributed by J. Mac Gregor, Montreal, Canada.