The Optical Magic Lantern Journal (December 1893)

The Optical Magic Lantern Journal and Photographic Enlarger. 189 tinct styles of entertainment. Mr. Keenig has been before the public for many years, and has met with one round of success. * at xe WE chance to know the opinions of some of the highest men of pure science in this country, about compressed oxygen accidents. One of those opinions is that bottles should be charged with gas to but about half the pressures now ordinarily employed, and less attention should be paid to portability. In the days of lower pressures, accidents were less frequent. Another opinion is, that it is not easy to secure the absence of grease about the nozzles of the bottles, because the floating dirt in the air is greasy, and whenever air or other gas flows through limited orifices, there is sure to be 4 deposit of grease. When any ventilating apparatus is fixed in the wall of a room, a greasy dirty area gradually appears around it. A third opinion, we have heard, comes from some practical lanternists; it is that the lever handles used for turning on the gas from bottles are usually too short, so that the gas can not always be turned on steadily, but may start with too much of a rush, which means unnecessary friction at and about the orifice. In relation to the subject of colourless glass for triple condensers, it may be mentioned that at a recent meeting of the Woolwich Polytechnic | Photographic Society, Mr. Henry Crouch, the optician, exhibited a beautiful slab of Jena glass, about six inches long, and which when viewed through its entire length was seen to be colourless. That particular glass may be too expensive for condensers, but it is to Jena that lantern condenser manufacturers must look with the best chance of success for a glass in every way suitable for their purposes. Professor Abbe and Dr. Schott are not likely to fail in relation to any matter they take up connected with glasses for manifold optical purposes. * * ¥* GREAT credit is due to Mr. W. D. Welford for his successful management of the Photo Section of the Stanley Show lately held at Agricultural | Hall. Nearly six hundred pictures were on exhibition, and about twenty firms made a display of photographic and lantern apparatus. Wirtu the next issue we shall publish the index for the yearly volume. x aS * A MERRY CHRISTMAS TO ALL. Cylinder Explosion. A rata accident happened on ‘the 8th ult. at the Exchange Station, Bradford. It appears that a boy, John Fuller, was carrying one cylinder of compressed gas on his shoulder, and dragging a second one along. From some unknown cause, he dropped that which he had on his shoulders upon the concrete floor, when immediately it exploded with a tremendou report, instantly mutilating and killing the messenger. From evidence at the inquest, we learn that the fractures were carefully examined by Professor Goodwin, of Yorkshire College, who found every one crystaline, with the exception of one, which he thought might have been due to a flaw in the material. In point of thickness the cylinder varied more than it should have, viz., from -172 to :184in., and in a well made cylinder this variation should be but slight. A second cylinder by the same makers, the Projectile Company, having been cut up, was found to be exactly of the same make as the broken one. Evidence was given that the steel of the cylinder was of very great tensile strength (50 tons), whereas that for such fo ae should not exceed 32 jtons per squaré inch. Steel of great tensile strength was unsuitable for the purpose, as it was so brittle. It was given in evidence that a cylinder of milder steel had that morning, by way of experiment, been dropped on to a block of cast iron from a height of 224ft., and that the only result was that the cylinder received a slight dent. After a great deal of evidence, the conclusion arrived at was that the cylinder in question was made of unsuitable metal. It is, doubtless, well known to our readers that cylinders of mild steel have stood very severe tests, both by internal pressure and by being allowed to fall from great heights, the only damage done in the latter case being a slight dent, while in the former case they have stood a pressure of over two tons, whereas the working pressure is only 1,800 Ibs. It is questionable whether it is advisable to submit ; cylinders to the high pressure at which they are tested, as this may, perhaps, strain the material ! unduly. ; As a preventive of any sudden concussion, i@ the jury recommended that when cylinders are sent out they should be protected either in cases or Otherwise. A variety of suitable coverings : for cylinders are to be found in rubber, woodite, | and other substances, but, considering the many ' thousands of cylinders in use, and the correi sponding freedom from accidents, it is doubtful if coverings for cylinders will be generally | adopted, unless the railway companies refuse to P