e pipes and other connections are
all 1/2-in. and the lengths of the pipes are made suitable for the
size of the camera. When a small object is to be photographed it
is placed upon the glass table and the background fastened to the
board. In this manner small objects can be photographed without
any deep shadow on one side. The bottom cross and ells should be
corked so as to prevent any slipping and damage to the floor.

** Home-Made Pocket Lamp [149]

A simple and safe pocket lamp that will last for about 6 months
without extra expense can be made at home for a few cents.

Have your druggist take a strong vial of clear glass, or a pill
bottle with screw or cork top and put into it a piece of
phosphorus about the size of a pea and fill the bottle one-third
full of pure olive oil that has been heated for 15 minutes--but
not boiled. Cork tightly and the result will be a luminous light
in the upper portion of the bottle. If the light becomes dim,
uncork and recork again. The lamp will retain its brilliancy for
about 6 months. This makes a perfectly safe lamp to carry. These
lamps are used by watchmen of powder magazines. Care should be
exercised in handling the phosphorus, as it is very poisonous.

** How to Make a Tangent Galvanometer [150]

Secure a piece of wood 1/2 in. thick and cut out a ring with an
outside diameter of 10-1/2 in. and an inside diameter of 9 in. and
glue to each side two other rings 1/4 in. thick with the same
inside diameter as the first ring and 11 in. outside diameter,
thus forming a 1/4-in. channel in the circumference of the ring.
If a lathe is at hand this ring can be made from a solid piece and
the channel turned out. Cut another circular piece 11 in. in
diameter for a base. Make a hole in the center of this piece 1 in.
wide and 6-5/16 in. long, into which the ring first made should
fit so that its inner surface is just even with the upper surface
of the baseboard. The ring is held upright in the hole by a small
strip screwed to the base as shown. All screws and brads that are
used must be of brass. The cutting of these circular pieces is not
so difficult if a band saw driven by power is used. They can be
cut by means of a key-hole saw if a band saw is not accessible.

Before mounting the ring on the base, the groove should be wound
with 8 turns of No. 16 double cotton-covered magnet wire. The two
ends may be tied together with a string to hold them temporarily.

Fasten two stri