The Optical Magic Lantern Journal (January 1897)

The Optical Magic Lantern Journal and Photographic Enlarger. 3 which the lecturer pointed out that the excellence of slides depended on the quality pictorially and technically of the negative, and in this connection he remarked that at the present time there seems to be a tendency to produce thin negatives, owing to the extensive use of gelatino-chloride papers. Such a character of negative was not well adapted for the best transparency work, although a good deal could be done in the way of obtaining passable results from such negatives by skilful manipulation. From a fully exposed negative, for instance, a crisp result can be obtained by under-exposing the transparency slightly; or from an underexposed negative the harsh feeling caused by too strong contrasts can be rectified by fully exposing the transparency, though by doing so the key-note of the whole picture was lowered. ~ & Light Without Heat.— With several lantern experiments it is necessary to employ some means of preventing the heat rays from reaching the object or slide, and to this end an alum trough—or what is just as effective, a water trough—is used. With ordinary glass alone, the percentage of heat rays that pass through is about 85 or 86, but it appears that a new glass has been invented in Germany which allows only four per cent. of the heat rays to pass through, whilst the light rays are practically not obstructed. This new glass is said to contain about 28 per cent. of iron in the form of ferrous chloride. With such it would only be necessary to place a piece in front of a condenser which will dispense with the use of the present troublesome trough. Bead o ~ Tin-Pot Lanterns.—Mr. Edgar G. Lee, in the course of an article in a contemporary, truly remarks: ‘‘ Men without experience of any kind think themselves competent to entertain a large audience by means of a cheap tin-pot lantern, a twelve feet almost transparent screen, and an oil lamp with a chronic smoky chimney.” ote te = X Rays and Tuberculosis.—From time to time various effects produced by X rays are being found out; one of the latest is their effect | upon some pigs inoculated with tuberculosis. Hight guinea pigs were thus inoculated, and | three were exposed daily to the X rays for an hour, these three grew fat and kept in good health, whereas the other five developed abscesses. Lantern Slides in Natural Colours. YAK \ i on LARGE business is done in the United States of America in connection with lantern slides which may be projected in their natural colours. A variety of such slides have been put on the market by Sy Messrs. J. B. Colt & Co., whose head Rs quarters are at Nassau Street, New York, with branches at Chicago, San Francisco, Boston, Philadelphia, St. Louis, Buffalo, and Atlanta, and with all these places of business it is quite reasonable to suppose that they get through a large number of slides of this particular kind. The slides themselves are devoid of colour, being to all appearances ordinary photographs. When taking the negatives, three are taken respectively through a red, blue, and green filter or medium. From these three negatives transparencies are made. These are mounted in one large frame, each slide being covered by a coloured medium of the same tint as that used when making its respective negative. This, then, is placed in a triple lantern of peculiar form and projected on the screen. Great nicety is of course required to correctly superpose the three discs, for to produce the correct gradations of colour all three pictures are projected at the same time. Such pictures form a series of stencil plates, through certain parts of which the coloured medium is allowed to show. The process is by no means new, but it appears that it has only lately been taken up from a commercial point of view and popularised. We described an apparatus for the projection of plain photographs in colours in this journal for February, 1891, but since that time many improvements have been made, and in connection with this process the name of Mr. F. E. Ives takes a prominent position. dies —QYBo<e Prominent Men in the Lanter) World. No. -111.—Mr. D. W. NOAKES, p \\HE moving spirit in the firm of eA RS Messrs. D. Noakes & Son, of VG \ Greenwich, is Mr. D. W. Noakes, 4 “| whose portrait we give. He has claimed acquaintance with lanterns the past thirty years, for at the age of eight he received the present of a toy lantern costing a few shillings ;