Motion Picture News (Sept-Oct 1921)

2032 Motion Picture New Buffalo Meeting of S.M.P.E. to B< Bigger and Better Than Ever Many Interesting Papers Scheduled to Be Read at Convention With the number of important discussions vi'hich will take place and the number of interesting papers which will be read, the fall convention of the Society of Motion Picture Engineers, scheduled for Buffalo, N. Y., promises to be bigger and better than any meeting yet held by the society. Besides the convention the annual meeting and election of officers will be held at the same time, October 31, November i, 2 and 3. Arrangements have been made by the committee to hold the convention at the Hotel Statler. Added interest has been created by the social program which has been mapped out. This will include among other events a theatre party and a banquet. The moving picture industry in general has been looking forward to the annual convention with great anticipation, and the announcement of papers to be read and their authors makes it appear that the gathering will be much more interesting than it had even been hoped. Dr. W. E. Story, Jr., has been making tests by which he has been comparing the relative efficiencies of large and small condensers, and his talk on these tests will be valuable and interesting. Dr. Story will also give a short talk on photometric measurements to determine the lighting of the motion picture setting before taking the picture. " Industrial Mechanigraphs " will be the subject of the paper to be read by Harry Levey of the Harry Levey Corporation. A film demonstration will accompany Mr. Levey's talk on this subject. L. A. Jones of the Eastman Kodak Company will talk on the effect of studio lighting on those working under it. " Analysis of Motion " will be the subject of the paper to be read by Charles P. Watson of Novograph Film Corporation. A talk on the " Commercial Applications of the High Intensity Arc " will be given by A. D. Cameron of the General Electric Company. C. A. B. Halvorson is going to demonstrate a " Point Source of Light." One of the most interesting events on the program will be a demonstration of pictures which C. Francis Jenkins has taken with his high speed camera at the rate of 1,500 per second. Following is the synopsis of a paper on optical glass which will be read at the convention by H. N. Ott of the Spencer Lens Co. : The glass used in lenses of the earlv times was glass selected from the regular commercial glass. LTntil Abbe's time in the early eighties no special attention was devoted to the making of optical H. A. Campe, president of the Society of Motion Picture Enqineers glasses for their specific purposes. From that time on very careful consideration has been given to producing varieties of glasses for different purposes and to perfecting these glasses in regard to homogeneity and freedom from striae, flaws and stones. With the exception of a little optical glass made in 1893 no optical glass was made in this countiy before the war. Some experimental work was seriously taken up in 191 2 which resulted in a little glass of indifferent quality. This production was improved from that time to 1917. It was only after the problem was seriously taken up by the Geophysical Laboratory of the Carnegie Institution and by the Bureau of Standards that any real progress was made. This was the beginning of a development which in three years has permitted us to make glass equal to the European product — and in some instances better — they have been at work on the problem for forty years. Part of the credit for this progress is due also to firms which co-operated with the scientific institutions just mentioned, viz. The Bausch-Lomb Optical Co., The Keuffel & Esser Co., The Pittsburgh Plate Glass Co. and The Spencer Lens Co. Optical glass is now being produced I this country in variety and quality ful equal to the products of all the Europe; producers. We have found domesi clays for the pots and sand for the gla equal to any, and are making chemicj of equal purity. All optical glass is made in pots, most instances where the high grade gla for critical lenses is concerned the gla is allowed to cool in the pot, and the p ; broken to secure the glass after it is co(! These pots are pre-heated for >ever days to gradually bring them up to tl| temperature necessary for the furnac After the glass is made in the furnai| the pot is removed to one of the pre-heal ing furnaces which has heated up anoth ' pot; then pot and furnace are allowed cool gradually for several days. The " batch " is gradually filled in the pot after it has been placed in tl large furnace. After it is in a fluid cc dition the mass is carefully stirred, tl stirring diminishing as the glass is som' what cooled preparatory to removing from the furnace. When the pot of glass is cool the wal of the pot are broken away from tl glass and the chunks of glass of vary-ii sizes are carefully examined for any ir perfections. If the chunks are too larj for the purpose, they are broken, ca being taken to break away any parts wi flaws. The refuse glass is thrown awa or remelted. After the chunks are prepared they a gradually brought up to a heat where th< are plastic. The mass is then moldt to a rectangular slab, two opposite edg of which are polished for more caref and critical inspection. This polishing done after the slabs have been careful annealed in cooling. If no imperfectioi are present the glass is ready for the ma ket. These slabe are used for makir small lenses. If large lenses, such as telescope lenS' of the refracting type are involved, tl process is the same except that great' care and longer periods of annealing a necessar}' because of the greater ma? It is necessan. to start with a mass Ian enough so that after removing the ir perfections, there is still enough in 01 piece to make the lens blank. Mai times several moldings and annealin; are necessar} to get finished disc fr' from flaws. Where reflectors for large reflectii telescopes are wanted the glass is poun from the pot into a circular mold of t! (Continued on page 2034)