The Optical Magic Lantern Journal (September 1893)

__The Optical Magic Lantern Journal and Photographic Enlarger. 123 A Walking Skeleton Slide. At the time we gave the description of the slide of Cupid, we stated that we would next give particulars of the above slide. This slide, like the former, is the property of Mr. Hill, by whom it was designed ; it was used at the Royal Polytechnic, and has never before been explained. It is avery effective slide, but to see it in the correct style, the Jantern requires to be slightly drawn further from the screen at the time each step is taken, this gives the effect of its advancing towards the audience. Fig. 1. Like the previous sketch, this one is also drawn in exact proportions, so that there need be little trouble experienced in making it. The upper portion of a skeleton having been drawn as shown in Fig. 1, the glass beyond the figure should be rendered opaque by varnish for the purpose, leaving the lower portion of the glass clear, so as to allow of the manipulation of the legs. To the edge of this circular glass should be fastened a lever, E, so that a slightly rocking movement may be imparted to the glass when this lever is moved. After this has been fastened in the wooden frame, a piece of glass of the relative size and shape of Fig. 2 should be cut and rendered opaque at the parts shown. This then is firmly secured in the frame with pins, close to, but not touching the circular glass. Next cut two pieces of glass as in Fig. 3, and cement to the edges a couple of stout pieces of cardboard, at the ends of which bore holes, B and C. The legs having been sketched and the remaining parts of the glass obscured, the slide is completed with the exception of a couple of stops, which may be formed of a few thicknesses of cardboard cemented on the circular glass (Fig. 1), at A.A., after which the two parts of Fig. 8 are secured by screws on the frame at the places indicated. When the lever D is slightly depressed, the body portion of the figure will incline towards the mght, and, in doing so, the stop A will cause the glass of Fig. 3 to be depressed, making Fig. 3. the corresponding leg to increase in length, which gives it the appearance of taking a step forward. When the lever E is returned to its normal position, the glass on which the leg is sketched (being connected to D by an elastic band) also goes back to its original position. In this manner, by moving the lever up and down, the body slightly oscillates, and each leg in turn becomes elongated and then returns to its previous position ; thus giving a very natural appearance of walking forward. :0:——— Sensational Guriosities in Optical Projection. Dunne the last session of the scientific societies of this country, two demonstrations in optical projection attracted considerable attention. One of them was exhibited for the first time in the history of the world at the Royal Institution, and has not been seen since, for the expense thereof is great. Professor Tyndall, in times past, has sometimes at the Royal Institution, in the course of experiments on the absorption and transmission of heat, taken a beam of light from the electriclantern, passed it through a trough of water with parallel glass sides, then brought it to a focus by means of a lens of ice, and with the concentrated rays thus passed through ice has fired gunpowder and other substances. During the last session Professor Dewar performed a still more remarkable experiment ; his lens for condensing the rays was not of ice but of quid