The Optical Magic Lantern Journal (May 1890)

The Optioal Magic Lantern Journal and Photographic Enlarger. gt too near the condenser, and that it must be withdrawn until this mark disappears. By gradually adjusting the position of the flame sideways, up and down, and to and from the con! Fic. 43. denser, all these markings will vanish, leaving the disc evenly illuminated ; and although it is nota difficult matter to centre the light, a want of harmony is produced if it is not correctly managed. Yand Cameras for Obtaining Slides for the Lantern, No. 1.—THE “GIAH.” THe “Giah” is to the ordinary camera what the breech-loading rifle is to the old muzzle-loader, when we consider the ease with which photographic ‘‘ shots ” may be taken; in fact, considering that one of the main features in it is the rotary slide, it may be termed a “revolver.” It is the invention of Mr. Chas. Winter (the London representative of Messrs. Mawson and Swan), who also acts as its godfather, seeing that the euphonious name of ‘* Giah” is Welsh for winter. The inventor has not copied or improved any existing camera, but has carefully thought out and executed an entirely new and original apparatus. There are no sheaths, changing-bags, or other detached parts. In loading, the front of the camera is opened, and a dozen plates —requiring no “ backing’—can be at once placed film downwards in the grooves at the top. When the last plate is in, it glides easily into the top groove in the rotary slide, and a light flap, or catch, prevents its return. A quarter turn backwards of the handle attached to the axis of the rotary brings the plate in the right position for exposure, and by a recent improvement the “quarter turn backward" cannot be given unless the plate has been properly discharged into the slide. After exposure another quarter turn backward brings the plate to the bottom of the camera opposite its place on the lower part of the lift of grooves, into which it is readily discharged bya slight tilt downwards. By this time the second unexposed plate at the top is ready to glide into the rotary slide, and the ‘‘ quarter turning” is repeated until the whole of the plates are exposed, and deposited in the lower set of grooves. A reference to the annexed diagram (Fig. 1) will aid the reader in following these movements, which are extremely easy in practice. if UNEXPOSED PLATES EXPOSED L Fic. 1. In order that the quarter turns may be made accurately there are four V-shaped notches, at equal distances apart, in the circumference of the volary slide, into which a small stop falls with a slight click when the plates are in their correct positions, and these notches are measured so correctly as to be within the thousandth part of aninch. While, therefore, all the mechanism is invisible to the operator, he has the most complete command over the working of the apparatus. It may be stated that the “Giah ” is conspicuous by its unobtrusiveness. In thisit makes a very decided step in advance, for with the aid ofa specially designed shutter the lens remains hidden, except during the instant of exposure. The shutter has t strap connected with the c reality a metal strip. By turning this metal strip half a turn to the right the shutter is set ; but the lens still remains covered. It is now only necessary to touch a small knob at the bottom of the camera and the metal strip flies backwards, and in the meantime the plate has been exposed. The length of exposure may be adjusted by an index finger at the foot of the case, and an index at the side also shows the number of the plate ready for exposure. he appearance of being a part of a arrying handle, but is in 1 Fig. 2. An instrument of this kind offers a wide field of operations for those who are desirous of introducing variety into their sets of lantern slides. uvgi Ui)