CHAPTER X
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
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.
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.
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.
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!