The Optical Magic Lantern Journal (August 1889)

20 The Optical Magic Lantern Journal and Photographic Enlarger. The Screen. THE lantern during the past few years has become very popular, and the weakest part of lantern exhibitions to my mind is the sheet or screen. By many itis thought that anything will do, and the result is, no matter how good the slides are, if the screen is not of the proper kind the pictures are spoiled. The lantern is fast becoming an educational instrument, both in schools and colleges, and when used for this purpose there is but little difficulty in providing the best possible screen—viz., a whitewashed wall; but to general lanternists it would be rather difficult to Carry a screen of this kind about with them. The kind of screen most generally in use is the calico sheet, being easily packed up; but for amateur lanternists for home use a screen ' faced with white paper and mounted on roller and lath—map fashion—is by far the best ; foran ordinary room a Screen about ten feet square will be found ample. It must be borne in mind, the more Opaque the screen the better will be the result. In making a screen of this kind it is best to get a sheet of calico as stout as possible, and some of the stoutest white lining paper, which can be obtained of any dealer in paper hangings, and face the sheet with it; and to make astill better job of it willbe also to Paper the other side of the sheet, with the object of making it more opaque. After it is well dry, the face of the screen had better be distempered with zinc white (which is the purest white known) ; its extra cost over ordinary whitewash will well repay its use. It was a screen of this kind that I used at the Crystal Palace. For larger screens that have to be folded up, a screen of this kind is entirely out of the question, and the only thing to be done is to go in for the best calico sheeting obtainable, which must be as stout as possible. Sheeting of this kind can be obtained up to ten feet wide. In making a large screen, say twenty feet Square, a seam in the middle must be avoided, which is best done by putting a piece ten feet wide in the middle, and five feet on each side. It is best only to sew these seams ; On no account must they be run and felled, as the felling, z.e. where the double thickness is, will show as anintense white line right up the seams in every picture I am well aware that many have an idea that it matters not how thin a screen is so long as it is white ; to those who hold such an opinion, they will Gnd themselves wonderfully deceived if, by way of experiment, they will attach a piece of white cardboard to the back of the sheet, and then throw the light from the lantern on to the face of the screen ; if this be done they will find ; where the cardboard is—it will show an intense white patch, and the other part will be quite grey in comparison to the other part. With a screen of this kind, when fixing it, is to stretch or strain it as tight as possible ; and the best means I know of accomplishin_ this is to have the sheet bound on the back edges all round with strong linen venetian blind webbing, with /arge brass eyelets (having about a quarter of an inch hole in them), placed about half a yard apart, taking care to have the webbing double thickness at each corner and wellsewn. A screen in this way will stand an immense strain. All my portable screens are made in this manner. Tapes and slight brass rings are perfectly useless. If the lantern is to be manipulated from an opposite gallery, the screen is best perpendicular ; if from the floor, to get the best result it must be tilted—z.e., the bottom of the screen must be drawn back in accordance with the tilting of the lantern; and if the sheet is not strained perfectly tight like a drumhead, it will bag out in the middle, and the worst possible results produced, especially if there is not much depth of focus in the lenses. Many have an idea that the larger the screen the better, no matter the size of the room ; this is entirely a mistake. Then, again, the distance of the audience from the screen is scarcely or never considered, which is very important. The front row ought never to be within the length of one diameter of the picture from the screen, and the other part of the audience from two to four diameters ; if the room be larger than this, then the screen had better be of greater diameter if the best results are aimed at. I omitted to mention that the bottom of the screen must not be less than three feet from the floor of the room. I may at some future time have something to say upon lenses, light, &c. Wm. BROOKS. Anecdote of David Livingstone, the African Explorer. ERHAPS a lantern story associated with LivingP stone may prove agreeable. On the last occasion of visiting this country Livingstone naturally gravitated to the home of his childhood, Blantyre, after which, and before returning to the Dark Continent for what proved to be the last time, he Stayed for a while in Edinburgh beside his daughter, who was being educated there. During that brief residence he looked in one day to the place of business of the late W. D. Clark, then vice-president of the Edinburgh Photographic Society, where he met his early friend, enthusiastic admirer, and munificent supporter, the late James Young, of Limefield, of paraffin fame. They had been friends in youth, if not also schoolfellows. After a pleasant chat another friend came in, the late Robert Bryson, Master of the Merchants’ Company, &c. The names are mentioned, as all of them save the narrator are now dead. After a short period dinner was suggested by the hour and the need for it, IP er eee SOOT SC OA reg