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70 MODERN MAGIC LANTERNS.
The arrangement of lantern and screen just described is
most suitable for a large audience, where a disc of several
feet in diameter is desired ; to show slides to twenty or
thirty people, a far more convenient plan, and one which will
give in general more satisfaction, is that of Fig. 56. Here
the screen is between the audience and the lantern, and
should be on a much smaller
scale to give the best effect.
In many private houses are
A
to be found two rooms
separated by folding doors
(Fig. 56) F F. Such a place is
admirably suited for this
arrangement, the spectators
occupying one room, the lantern
the other, and the screen
being placed in the opening
of the doors. A thin sheet,
especially if wetted, makes
a good screen for this purpose,
but one much better
in every way, if its size is
not considered a drawback,
can be made of tracing
paper or cloth. This can be
obtained in 5-ft. widths,
possibly larger, and is easily
stretched and fastened over
a light wooden frame with
drawing pins. With an oil
lantern with a disc of about
4 ft. 6 in. in diameter on
Fig. 56. such a screen a result of the
ARRANGEMENT OF LANTERN,
AUDIENCE, AND TRANSLUCENT SCREEN.
most brilliant nature is
obtained, and the slides are
seen to much greater advantage than they would be if
shown reflected on an ordinary sheet with twice that
amount of enlargement.
A method of displaying slides for advertising purposes
we have seen carried out with great success is shown
THE SCREEN AND GENERAL ARRANGEMENTS. 71
in Fig. 57. The lantern, A, in this case is inside a
room, the window of which, freed from sash frames and
bars, is occupied by a blind of tracing cloth, B, which can be
drawn down for the occasion, the fittings being those of the
ordinary roller blind, c c. The screen is protected by a
weather-board, D. The slides are alternately photographs
of stage and other beauties, and subjects more immediately
connected with the wares of the firm employing the lantern.
For such a purpose a blow-through or oxy-calcium jet gives
ample illumination ; in fact, excellent results can be got with
Fig. 57. LANTERN USED FOR ADVERTISING,
the use of a good petroleum lamp. If the window looks out on
to a street brightly lit with the electric light, the direct light
from the lamp-posts must be cut off, or the light in the lantern
considerably increased, if brilliant results are wanted.
For teaching purposes, a large sheet of plain white cardboard,
or a sheet of drawing paper stretched on a board
with drawing pins, makes a convenient screen for a small
class. The smaller the screen the brighter the light, and
in consequence, the less need there is to darken the classroom.
For many purposes it will be found that all that is
necessary is to stand the screen where the direct light from
the window does not fall upon it, for the diagrams, etc.,
which would be the class of subject oftenest shown under
such conditions, to be easily visible in daylight.