SCREENS AND SCREEN STANDS
The best of all screens for lantern purposes is undoubtedly a smooth
whitewashed wall, and this is now provided in many halls where lantern
exhibitions are usual. In places where this is not practicable the next
best substitute is a canvas {80} screen, which rolls up and down (Fig. 48).
This can be obtained from any good maker, but again can only really be used
as a _fixture_ in the hall where the lantern is to be used. It can,
however, be fitted into a wooden box which can be painted or varnished to
suit the other architecture, and the provision of such a screen is to be
strongly recommended whenever possible. If portability is required, a linen
or calico sheet that can be folded up is necessary, but this can never be
hung absolutely flat, and also loses a considerable amount of light by
transmission.
[Illustration: FIG. 48.--Roller Screen.]
A so-called 'transparent' sheet is made of very thin linen, and intended to
work with the lantern _behind_ it, showing the picture through the linen to
the audience on the other side, but this is seldom used except in the open
air for religious or political meetings, &c.
An _opaque_ sheet can be had in one piece up to 9 feet square; larger sizes
than this must have at least one seam, and most skilful sewing is
necessary, especially with large sheets consisting of several strips sewn
together.
Sheets such as these are usually supplied with either eyelet holes round
the edges or else linen tapes sewn on, and the exact method of hanging must
be left to circumstances. {81}
In the case of a small sheet it will be sufficient to stretch it at the
four corners, and this can often be done by screwing into the walls or some
convenient girder two screw eyes and similar eyes into the floor, all four
being considerably farther apart than the size of the sheet.
[Illustration: FIG. 49.--Portable Screen Stand.]
A stout cord being then passed through the two upper eyes, long enough for
both ends to reach near the floor, one end of each can be fastened to the
two top corners of the sheet and the latter drawn up, the two bottom
corners being afterwards stretched and tied down tightly to the lower eyes.
In the case of large sheets this hardly suffices, and it will be found
necessary to fasten the sheet at intervals all round or it will exhibit
awkward creases, and this again is a matter where the lanternist must use
his own initiative according to the possibilities.
In some halls the erection of a sheet in the way above described is a sheer
impossibility, and in such cases a frame must be made by nailing strips of
wood together, or better by utilising a portable screen stand (Fig. 49).
These stands are usually made of bamboo, with short brass connecting tubes,
and the method of using them is so obvious that a description need hardly
be given. The screen frames are supplied by all the leading opticians, but
an intending purchaser would be well advised to see one erected before
ordering. I have actually seen a 12-foot screen frame offered for sale that
was too weak to carry its own weight, let alone the weight of the sheet!
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