The Optical Magic Lantern Journal (September 1892)

100 The Optical Magic Lantern Journal and Photographic Enlarger. Warn on a visit to the Kast, the Crown Princess of Norway and Sweden took over 2,000 negatives with a hand camera. Lantern slides are to be made from the best, and her Royal Ilighness is to give a series of lantern entertainments to her friends during the winter. * we * It is estimated that about 300,000,000 hen’s eggs are used in the United States annually in connection with the manufacture of albumnized paper. * No Eg RECENT experiments demonstrate that zinc oxide when incandescent becomes exceedingly luminous at a temperature above 880° Cent. | The phenomenon belongs to a class described as the ‘‘ Phosphorescence of heat.” This abnormal brightness, which is due to something else than ordinary incandescence, has been observed in other oxides. Cylinders of lime, when freshly ignited in the oxy-hydrogen flame, also exhibit a momentary brilliance not afterwards observed. The brightness of the magnesium flame may be of 8000° Cent, yet the actual temperature of the flame as measured, is only 1400° Cent. The phenomenon like ordinary phosphorescence is a inystery at present. THe manufacture of artificial india-rubber for tubing and other purposes has lately been protected by patent. The component parts of this composition are manilla gum, benzine, bitumen, and resin oil. It is said that the product obtained from careful admixture and special treatment of these materials gives a substance which possesses all the elasticity, solidity, and suppleness of the finest india-rubber. We have all heard of the power of the sun’s rays. Tn New York latcly, these, by the agency of lenses ; recently sct fire to a building and damaged about fifty pounds worth of goods. It appears that the lenses of a Solar enlarging apparatus of Messrs. Rockwood & Co., were left uncovered when not in use, these focussed the solar rays on woodwork, the result of which is stated above. THe New York Recorder is endeavouring to increase its circulation by giving a hand camera together with a copy of the paper for a specified time for a certain amount. * * * THE camera mentioned in the foregoing paragraph, is evidently of a totally different kind from any thing hitherto introduced :—According to the description which the owners of the paper give, “It is incased in ebonite with an achromate lens. That means that it can take pictures at any distance beyond eight feet without any troublesome focussing .... push a string and turn a key.’ A testimonial from the Editor of the Camera and Tripod then follows, in which he explains that pictures taken with these cameras, ‘‘do not have the distortion and bad perspective found in other fixed focus cameras.”’ It might be interesting to know the relation of the covering of the camera, &c., to the distance beyond which objects are in focus, also in what way this particular camera differs from the others spoken of by the Editor of the paper mentioned. Stereoscopic Effect with BiUnial Lantern. By Oxre wHo was Seen It. Sincr Wheatstone, over fifty years ago, startled the scientific world by his theories of binocular vision, and the invention of the reflecting stereoscope, many attempts have been made to apply the principle to pictures projected upon a screen from optical lanterus. In the greater number of these attempts the two pictures of a stereoscopic pair have been projected side by side, or one above the other, and a pair of prisms used to reflect one picture only to each eye. Obviously, to effect this satisfactorily, the observer must be in one position, and any system, therefore, of this character, must fail in the one important point —that a number of observers cannot see the effect at the same time. To overcome this difficulty the two pictures can be superposed upon the screen, but how then can one picture, and one only, of the two equally bright picturcs be conveyed to the right eye and the other to the left eye? It must be remembered that it is a necessity of stereoscopic yision, that one picture of the pair fall upon the retina of one eye, and the other picture upon a corresponding portion of the retina of the other. This was the problem to be solved with superposed pictures, and hitherto no satisfactory solution of it has been made. To overcome the the difficulty the inventor of the new system, Mr. John Anderton, of the firm of R. Field & Co., Opticians, Birmingham, takes advantage of the peculiar properties possessed by polarised light. It would be out of place here to refer to the nature of light when polarised, it must suffice to state that ordinary light, after passing through certain substances, or after being reflected from certain materials, is found to have undergone a great and mysterious change.