The Optical Magic Lantern Journal (January 1890)

60 This is not the only advantage of the benzoline imelight; besides being more powerful, it is cheaper than ether, or even coal gas, if the wear and tear of the gas-bag is considered. Good ether costs about 15s. a gallon; benzoline about 1s. a gallon. Thecost of ether fora limelight of 400 candle-power may be put at 6d. or 8d. per hour; benzoline gives a limelight equal to 600 candles at a cost in fluid of about one halfpenny per hour. Coal gas costs 3d. per hour, reckoning 200 exhibitions as being the lifetime of a gas-bag. These figures exclude the cost of the oxygen. Ihave obtained provisional protection for a benzoline saturator. This is placed ina bath of warm air, heated by a night-light or fairy lamp, burning ten hours without attention. 1 formerly used a water bath, but prefer the air bath for its simplicity, and also because when properly made there is no fear of the Saturator getting too hot, and causing thereby unsteadiness of the light. ALPERT Wa. SCOTT. 10: Flashes on Lantern Topics. LANTERN SLIDE MOUNTING.—At present this seems to be a burning question ; and of a'l the methods mentioned lately, that introduced by Vevers, of Leeds, and to which attention was drawn in your last, composed of different coloured strips, seems about the best, the present almost universal black being the worst. I think a much better, although far older, thing is that which I have had in use for, shall I say, uncounted ages Instead of any coloured mount whatever—which in the indistinct light at the lantern might be misleading, and are somewhat annoying, if not deceptive—I have used strips of plain white paper of firm body, and not gummed, but pasted on with common flour paste, which adheres to glass much better than gum, dextrine glue, or any such dried coating on the paper, and is quite as handy to use. On the top edge is written or printed in as large letters as possible the names of the set, suchas Egypt, Palestine, &c. ; andon the proper front at the top, which is the one which looks into the lantern, is put first at. the one corner the consecutive number of the set, which is constant, and on the same line the special title of the subject, leaving space at the opposite corner for an affixed number, which may be removed at pleasure ; the running number of the set is also put on the top edge with the general title series. The use of the affixed numbers is to make a running set of numbers when the sets are not shown in consecutive order, but mixed, it may be, indiscriminately. This method, it will be seen, keeps each set to itself, while allowing every latitude for interchange with separate sets. Another wrinkle may be noted in this connection which I have found very useful. With every slide I | tion according to circumstances. The Optical Magic Lantern Journal and Photographic Enlarger. have a card of the same size, on which all the material notes for description at the screen are carefully and legibly written, and they are titled and numbered as the slides are, and kept with them in the same boxes till wanted. These, after the subject has been read up and noted in this way, form quite a compendium, and each slide has its own story at once to hand, which can be used after the introductory portion of the lecture has been got through in a longer or shorter verbal descripIf the idea is worth anything, there it is, and I believe Dr. Nicol (of your contemporary ‘“‘The Beacon,” U.S.A.) and myself may claim the joint credit (if any) of originating and first using this method. The whole set of cards describing a lecture may be held in the hand as easily as a pack of playing cards. The movable numbers should be on gummed paper of a markedly different colour. I have found black, with white opaque ink, very suitable. They may be either square cut with the scissors, or what is neater, punched with a circular punch, having a bit of hard close-grained wood on end as a bolster or anvil. Very slight damping attacks or removes these temporary numbers without affecting the white mounting paper or card. While on this subject, it may also be mentioned that since adopting boxes with acouple of strips of rubberband tubing on the bottom, and a loose lid with a spring attached on the top, under a sliding one, I have never had a break, although they have sometimes had pretty rough journeys. In No. 3 I find that I have inadvertently done Professor Muybridge injustice, in assuming that he had not studied the prehistoric drawings, or rather engravings, of animals in motion, on horns, tusks, and other materials. Having made this mistake, and found mine, the retractation (although unasked) is most cheerfully given, accompanied by the hope that I may soon have the pleasure and profit of seeing his pictures shown by the Zooprasiscope (as his lantern is called), and hearing his exposition thereof. The first set I had the pleasure of exhibiting were those of the horse in motion only : they were very perfect, as well as curious and instructive, but simply shown by the ordinary lantern. BULL’S-EYE. 102 Lantern Slide Competitions. COMPETITIONS of slides have become of a very interesting character at many meetings of our photographic societies, and by the method to he described great delight is afforded, not only to the competitors, but also to the others present, who act inthe capacity of judges. Acertain set of negatives is lentin turn to those who desire to compete, and the transparencies handed in to the proper official at a stated time, with a mark on each slide so as to facilitate identification. As the