The Optical Magic Lantern Journal (April 1892)

The Optical Magio Lantern Journal and Photographic Enlarger. 47 tap quickly, the “off” picture stays on the screen for a perceptible space of time; and_ this appearance has always very much annoyed me. About two years ago I went to a lantern exhibition, where the lecturer used an ordinary bi-unial lime-light lantern. But he kept both lamps full on all the time, and dissolved with a fan moving up and down, covering first one lens, then the other. The effect on the screen was charming : one moment there was one picture to be seen, the next moment it was another. The change was So quick, so instantaneous, that it eluded the eye, and all one could see was a kind of flash on the picture, and lo! ‘it was different. But some one will say, what a waste of gas to keep both lamps going all the while; and besides, one's slides are exposed to the heat for twice ‘as long a time, and over-heated slides will sometimes crack in cooling. Quite so, but any one who disregards expense and does not mind risking his. slides, cannot do better than “dissolve” in this way, and he can have instantaneous or slow dissolving quite at will. But wishing to produce thissplendid effect, and, being equally desirous of saving my gas, I thought the matter over, and soon lit on a very simple plan for combining both these things. I simply use a fan jointly with a dissolving tap. The fan covers the “off” lantern lens, and the tap turns down its light. The fan is connected by a hinged wooden rod to the dissolving tap, and being fastened to one-end of the lever which turns it, when I turn the tap the fan moves simultaneously. The result is that there is none of that unpleasant fading out of the “ off”’ picture— it is gone instantly and completely, and if you let a little more oxygen than usual through the by pass, the lime lights up full directly, and there is no falling of the light. Of course this arrangement does not prevent your having both lamps full on when you want them, and you can also dissolve just as slowly as you please for a transformation effect. The accompanying diagram will, I think, sufficiently show the apparatus. end of the tap-lever moves in an arc of a circle, so that the rod is prevented from having a per| The. fectly perpendicular up-and-down motion. rod in no way interferes with removing the slides, and the fan should be made as light as possible, otherwise its weight may turn the tap when it is not wanted to be turned. No doubt modifications will be necessary to suit the pattern of other lanterns, but all you have to contrive is that the turning of the dissolving tap shall at the same time shift the fan from one lantern to the other. If this tap is screwed on to the lan tern body, it will be better to remove it and fix it to the box, just a little to one side, as shown in the drawing. My tap was originally on the lantern, but the pipes got so much in the way when I was adjusting the jets, that I removed it and fixed it to the box. Many people who see this arrangement for the first time, say to me, ‘ How well your lantern dissolves !” 30: Improved Carrier. In the semi-darkness that is usual at a lantern exhibition one sometimes experiences a difficulty in readily inserting the slides into the slot of the ordinary lightning form of carrier. Mr. J. C. Oliphant, in the course of school demonstrations in Edinburgh, found this difficulty a great hindrance to successful manipulation, and has devised an alteration of the carrier, which, like most good things, is very simple. As this gentleman has kindly forwarded for our inspection a carrier altered to suit his requirements, we have pleasure in showing how the improvement may be made. The upper portions of one side of the ¢o and fro carrier immediately above the slide opening are first cut completely away, after which the upper part of the rebates are trimmed flush with that portion in which the slide is inserted, an arrangement which will be readily understood by a glance at the cut. fs In order to place a slide in the carrier it 1s ‘only necessary to press it against the upper part The rod must : be allowed a little play at the pivot, because the | of the opening, and allow it to descend into its place. 30;. Toning Slides with Uranium : Salts.* By ALFRED STIEGLITZ. EXPERIMENTS in toning slides with uranium salts have led me to adopt the following simple working methods :— ; Give full exposure, and develop with any — ordinary developer until the slide looks some Read before the Society of Amateur Photographers of New York.