aply as follows: For the case use an ordinary 1/2-lb.
baking-powder box with a piece of heavy wire soldered on the
inside, 1-5/16 in. from the bottom. For the magnet use a piece of
round hardened steel about 3/8 in. in diameter and 1-1/4 in. long.
If desired, a piece of an old round file may be used for the
magnet core, which should be magnetized previous to assembling,
either by passing a current of electricity around it, or by direct
contact with another magnet. The steel core should be wound with
about 250 ft. of No. 36 insulated wire, the ends of which should
be soldered to a piece of

[Illustration: Telephone Receiver]

lamp cord, passed through a hole in the bottom of the can and
knotted inside to prevent pulling out.

A disk of thin sheet-iron, such as is used by photographers for
tintypes (Ferrotype), should be cut to the diameter of the can,
taking care not to bend the iron. The magnet should then be placed
in the bottom of the can in an upright position and enough of a
melted mixture of beeswax and resin poured in to hold it in
position.

While the wax is still in a plastic condition the magnet should be
located centrally and adjusted so that the end will be 1/16 in. or
less below the level of the top of the copper ring.

After the wax has hardened the disk is slipped in and fastened
tightly by a ring of solder when the instrument is ready for use.

** How to Bind Magazines [56]

An easy way to bind Popular Mechanics in volumes of six months
each is to arrange the magazines in order and tie them securely
both ways with a strong cord. It is well to put two or three
sheets of tough white paper, cut to the size of the pages, at the
front and back for fly leaves.

Clamp the whole in a vise or clamp with two strips of wood even
with the back edges of the magazines. With a sharp saw cut a slit
in the magazines and wood strips about 1/2 in. deep and slanting
as shown at A and B, Fig. 1. Take two strips of stout cloth, about
8 or 10 in. long and as wide as the distance between the bottoms
of the sawed slits. Lay these over the back edge of the pack and
tie securely through the slits with a string thread--wrapping and
tying several times (C, Fig. 2).

If you have access to a printer's paper knife, trim both ends and
the front edge; this makes a much nicer book, but if the paper
knife cannot be used, clamp the whole between two boards and saw
off the edges, boards and all, smoothly, with a fine saw.