The Optical Magic Lantern Journal (August 1898)

123 The Optical Magic Lantern Journal and Photographic Enlarger. The Lanternist’s Practical Cyclopedia.*—No. XXII. By CHARLES E. RENDLE. Réntcen Rays.—The discovery made by Professor Rontgen, of Wurtzburg, in November, 1895. It is stated that. he accidentally found whilst experimenting with & Crookes’ vacuum tube that a photographic plate which was enclosed in a dark box—the exterior of which was exposed to its rays—received an image of metal objects, whilst the box itself was transparent. ‘Further investigation soon established the fact that | these dark and invisible rays proceeded from the ‘cathode,’ though not identical with the streams of molecules called by some ‘cathode rays,’ that they | more or less penetrated all substances, roughly in inverse proportion to their density, and that they were incapable of refraction.” The news of so important a discovery spread like wildfire to every corner of the earth’s surface. No one for the moment believed, or even cared to believe, that science was on the verge of looking into their insides and saying, ‘' You are fearfully and wonderfully made, and if you don’t believe it, look at your photograph which I have in my hand here, and see yourself—your appearance as you are when inside outside.” This may be slightly exaggeruted, but not much, as every reader of these lines can testify. For by this process of photography you are privileged to take the image of your own skeleton without being put to the inconvenience of undressing. Perhaps never in the world's history has a discovery been more rapidly sought after, adcpted, and turned to better . purposes than has the Réntgen rays. The modus operandi of the process, the perfection to which it has been brought, and the uses to which it has been applied have been discuased in detail from time to time in the pages ; of the OpricaL Macrc Lantern JouRNAL, Vol. ViL, pages 19, 49, 77, 107; Vol. VIII., pages 3, 194, etc., and forms interesting reading. RupseR Tupinc.—An outfit would be incomplete with| : Scigexck oF THE Lanrern.—The knowledge of its out a few lengths of flexible indie-rubber tubing, and should be carefully selected. The stoutest is best without the spiral coiled wire lining. This, of course, is purely from choice, but after many drawbacks in ‘ having the tube trodden upon, experience shows that | oftentimes it is destroyed, as it will not resume its : form, and sometimes breaks. The wire also corrodes when the oxygen gas contains traces of chlorine. sequently a return current is produced which is likely to cause explosion with mixed gases, unlese checked as above advised. Where the gas passage contains one, two, or more of these valves, gas once passed cannot return, therefore perfect immunity from mishap is insured. They may be purchased at the dealers for a few shillings. SaTuRatToRs.—An instrument or apparatus for producing & perfect substitute for hydrogen gas or coal gas, and by its employment the most brilliant and powerful form of limelight is obtainable. The advantages of the saturator principally are that only one gas (oxygen) is required for its working, that only one cylinder or gasbag has to be conveyed to the places of exhibition, and that the luminosity of the light is of an intensity that has not been surpassed by any other means (electricity excepted), if it has ever been equalled. A stream of oxygen gas is directed through a channel or series of channels that are blocked or packed with flannel, asbestos, or similar porous filling that has been previously soaked with some such volatile, inflammable fluid as ether, benzoline, etc. The oxygen takes up the vapour and will burn in air, whereas under ordinary conditions this is not so. It is this saturated oxygen that is the substitute for hydrogen, coal gas, or other flame, and when lighted up a second stream of oxygen is guided into it near the point of ignition, in the same way as the mixed gases are arranged. Although the saturator is not at all a new idea, it was not until 1891 that any real practical use was made of it, since which time, however, such experimentalists as Lawson (of Lawson saturator fame), of Parvin (of the Gridiron, now popular all over the world), of Timberlake, who for upwards of 30 years has been investigating the matter, and very many others have helped to bring to perfection the saturator of the present day. It would not be fair to here advise one make of apparatus in preference to another, the reader must settle that question as he or she may think best, always bearing in mind that the apparently cheapest at the beginning is often dearest in the end. principles, uses, and workings, etc. Sciopricon.—A term used principally in America for “magic lantern,” possibly taken from “ Scioptics,” the science of exhibiting material representations of external objects through lenses in a darkened chamber. ' Screexs.—A wall fpecially prepared for the purpose in a SaFeTy VaLvEs.—Valves fitted to boilers, etc., which open and act as exhausts for steam above a certain pressure, thus avoiding explosions and other accidents. There are times also whcn safety valves are recom mended to gas apparatus and connections, specially so — when gas-bags are employed, for producing the oxyhydrogen light. There are cases when the bags have to be placed at a distance from the lantern, and the , india-rubber tubing joined up by connectors, which are lengths of metal tube 3, 4, or more inches long. These tube connectors are much more advantageous if fitted with a flat valve, on the spiral spring system, These are so simple and safe that they act as an absolute safeguard in working. It may here be stated that with gas-bags pressure is added liberally in the form of weights being placed on them; not only should the weights be identical on both oxygen and hydrogen bags, but also the bags should be of the same dimensions, to insure the pressure being equal. any chance accident a weight be knocked off pressure on that gas is suddenly diminished, and con * All rights reserved. Should by |! a bag the | building where the lantern is permanently located is the best screen in every way, always flat and free from creases, and will keep clean for years if in careful keeping. When such a screen can be made, it may be to advantage to incline the wall inwards, from top, at an angle of 1 inch to the foot, therefore, if the wall be 12 feet square it would be 12 inches out of the Perpendicular at its base. This cannot always be arranged, in which case the lantern should not be tilted, because the centre of the light’s rays should strike the centre of the screen in a true horizontal line. In dealing with screens and their fittings, it is an experience that has caused as much discussion as any other branch of a lanternist’s work, in consequence of the great quantity of paraphernalia in the form of frames, trappings, rollers, etc., recommended, until it behoves the practical worker to adopt the mode of erecting @ screen in the simplest way to his thinking. If all screens were of one uniform size the problem would be more get-at-able, but as they are not, and never will be, the next best thing to do is to fix on a method which suits well on trial and stick to it. (To be continued.)