ch other. Place a screw eye about 1/2 in. from the edge
on each side of these openings. Fit an axle in the screw eyes and
fasten a spool to the middle of the axle. On one of the two spools
attach another smaller spool, Fig. 2, to be used as a driving
pulley. Cut out the front part of the box down to a level with the
top of the spools. Connect the spools with a belt made from tape
about 3/4 in. wide. On this belt fasten figures cut from heavy
paper and made in the form of people, automobiles, trolley cars,
horses and dogs. A painted scenery can be made in behind the
movable tape. The front part of the box may be draped with
curtains, making the appearance of the ordinary stage, as shown in
Fig. 3. A small motor will run the spools and drive the tape on
which the figures are attached.
--Contributed by William M. Crilly, Jr., Chicago.

[Illustration: Details of Stage]

** A Floating Compass Needle [160]

When a thoroughly dry and clean sewing needle is carefully placed
on the surface of water the needle will float even if the density
of steel is 7 or 8 times that of water. A sewing needle thus
floating upon water may be used as a compass, if it has previously
been magnetized. The needle will then point north and south, and
will maintain this position if the containing vessel is moved
about; if the needle is displaced by force it will return to its
position along the magnetic meridian as soon as the restraint is
removed.

** Home-Made Dog Cart [160]

The accompanying photograph shows a boy with his "dogmobile." The
photograph was taken when they were on a new pavement which had 2
in. of sand

Dog-Power Cart

left by the pavers and a grade of 6 per cent. The machine is
nothing more than a boy's rubber-tired wagon on which are mounted
a box for a seat and a wheel steering device extending above and
below the board of the wagon. The front wheels are guided by ropes
attached from each end of the axle and a few turns around the
lower end of the steering rod. A pair of shafts are attached to
the rear, into which the dog is harnessed.

** How to Make a Dry Battery Cell [160]

[Illustration: Dry Battery Cell]

Dry battery cells are composed of the same materials for the
poles, but instead of the liquid commonly used a paste is formed
by mixing sal ammoniac and other salts with water and packed in
the cell so it cannot spill.

A cell of this kind can easily be made, and to make it the proper
size a sh