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68
MODERN MAGIC LANTERNS.
They will roll up into a fairly small compass, however, and
give a better result than can be obtained with any sheet ;
moreover, they do not want stretching, but merely to be hung
from their roller with a weighted rod along the bottom. In
large sizes, such screens have a tendency to bend, the edges
Fig. 54.
ARRANGEMENT OF LANTERN, AUDIENCE, AND OPAQUE SCREEN.
stretching more than the centre, which after a time may
render them almost useless.
In spite of its many drawbacks, therefore, the sheet remains
the sheet anchor of the lanternist, possessing, as it
does, portability together with an excellent flat surface and
a fair amount of reflecting power. It should be provided
with rings or eyelets, which must be securely stitched to its
edges every foot apart, by which it is hung and stretched.
THE SCREEN AND GENERAL ARRANGEMENTS. 69
A frame is the most generally useful means of stretching
a small sheet, say one not exceeding 8 feet square, but
above this size the frame, no matter how much it may take
to pieces for packing up and carrying, is a bulky affair, and it
is better to rely upon ropes. The method of stretching the
sheet with ropes is shown in Fig. 55, in which A is the sheet
suspended from its two top corners by the rope B B, which
passes over two pulleys in the ceiling (which must be further
apart than the width of the sheet itself), and thence is
fastened to the floor. Stout string is then tied to the top
corners and laced backwards and forwards through the holes
Fig. 55. METHOD OF LACING UP LANTERN SCREEN.
in the sheet and round the rope until the bottom corners are
reached, from whence the string must pass to the floor as
shown. While it is important to stretch the sheet sufficiently
to make its surface quite flat, more tension than is necessary
to effect this must not be employed, or, no matter how well
the eyelet holes are stitched to the sheet, they will soon
become loosened and tear off, bringing, it is most likely, some
of the sheet with them. The method of lacing described
may also be applied with advantage to the stretching of a
sheet on a frame, allowing, as it does, each side of the sheet
to be fastened with one piece of string and a single knot.