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50 MODERN MAGIC LANTERNS.
lamp are marked + A and A res ctively, the current is
taken from the two terminals + B andB; C is the switch,
D the resistance, and E the arc. A variable resistance is
shown in the figure, but if a suitable amount of resistance
is introduced, the power of varying it is not required, at
any rate under ordinary circumstances.
The most suitable wires for use with the lantern are
what are known as twin silk-covered flexible, in which the
two are insulated with rubber and silk, and twisted together.
Each main wire or lead is made up of a bundle of fine wires
to give the whole flexibility; for the lamps usually em loyed
in the lantern, each lead should have a carrying capacity
equal to a solid wire of 4 B.W.G.
CHAPTER IX.
Zbe 'lantern 1,6obp.
THE various illuminants for use in the lantern having
been considered, the body of the lantern, which is required
to cut off all stray light which would otherwise reach the
screen or the eyes of the audience, and which serves to hold
the various parts in their relative positions, next demands
attention.
In the case of oil lamps, the body is sometimes a part
and parcel of the lamp itself, but more often is a metal
case in which the lamp slides. The best material for the
purpose is Russian iron for the box portion, A B, Fig. 1,
and brass for the tubes H H, which carry the lens. In
lamps of the type of that shown in Fig. 6, the lamp itself
carries its chimney, which emerges through a hole in
the top of the lantern, and the body of the lantern is
brought down nearer to the lamp and so made more compact.
For dissolving views with petroleum lamps, the two lanterns
are placed side by side. The better class of instruments in
which oil lamps are used, have bodies made of mahogany
with brass fronts, and are fitted so that the lamp can be
drawn out, and the usual tray and jet substituted when limelight
is required. In such a case the lantern should have
an inner lining of iron separated from the woodwork by an
air space, to prevent the wood from getting hot.
Lanterns for limelight and for the electric arc should
always be made in this way. They should be provided
with a door on both sides as well as an opening at the
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