The Optical Magic Lantern Journal (March 1897)

46 The Optical Magic Lantern Journal and Photographic Enlarger. tenfold pressure, but the rate of propagation is much below that of the true explosive wave of such a mixture as electrolytic gas, that is to say of gas prepared by decomposing water with an electric current into its elements, oxygen and hydrogen gases. As the temperature due to the explosion increases with + initial increasing compression, it was to be expected that liquid acetylene would exhibit the character of a “high” explosive. This M.M. Berthelot and Vieille have shown to be the case. Eighteen grammes or rather more than 4 ounce of liquid acetylene, exploded in a steel bomb by & hot wire, developed a pressure of 5,564 kilogrammes per square centimetre. This corresponds to an explosion pressure for the liquid alone of about 9,500 atmospheres, & value approaching that of gun cotton. (To be oontinued.) Gif. Ott, The Largest Lantern Audience. Cred tC a] re) ROBABLY the largest and most disV tinguished audience that listened to A any lantern lecture was on the aN occasion of Dr. Nansen’s discourse Ws) — before the Royal Geographical & Society at the Albert Hall on the 8th é ult., when he gave a graphic description .u of his travels in the far North. What Dr. Nansen said has been fully reported in the daily papers, also the particulars of the speech by H.R.H. the Prince of Wales when he presented Dr. Society’s gold medal. taining to the lantern manipulations, we have pleasure in stating that the society and Dr. Nansen selected as their lanternist Mr. C. W. | Locke, and certainly they could not have had a more experienced operator. A stout rope of 24 inches in circumference was stretched across the hall by means of pulley blocks immediately | in front of the great organ ; on this, stout rings were fitted which carried a screen 37 feet 6 inches square, and even this in such a huge building did not look its size. It may be of interest to know that the raw material for this screen cost Mr. Locke between £8 and £9. During the introductory part of the lecture, the screen, gathered together, hung as a white strip, and on an electric signal from the lecturer, Mr. Locke, by a series of unobtrusive hand signals, gave his instructions. At the first the cord round the bottom of the screen was undone; on the second the screen was drawn across the rope; on the third the screen was rendered taut by fastening the corner ropes to rings in the floor, and on the fourth the lights were put out. All this was effected with great smoothness in a surprisingly short time, the lecture going on meanwhile. Nansen with the | As our readers will | probably be interested in a few particulars per| ' The lantern was placed in the Duke of Wellington’s box on the first tier, and was 167 feet distant from the screen, which the pictures filled, leaving only a very few inches of margin. At such an important demonstration as this the slightest hitch would have spoilt matters, and it was interesting to see the great precautions taken by Mr. Locke to guard against such. The oxygen and hydrogen cylinders with fittings were in duplicate, and at a moment's notice the extra set could be switched on, should such be necessary. Duplicate warm condensers were also in readiness in case of breakage ; although no such duplicates were required, it showed due caution on the part of the operator. The light, which was obtained by Mr. Locke’s new patent jets, was most brilliant. At the termination of the lecture, and before the presentation of the medal to Dr. Nansen, the signals were again gone through, and in a moment or so the hall was illuminated, and the screen hung, as at first, in a strip at one side of the building, and brought to a close one of the most important, unique and successful lantern lectures of modern times. eek SEY) {Qa Prominent Men in the Lantery World. No. V.—Mr. CHARLES E. RENDLE, G 4 NDER this heading, in our previous 2 chapters, we have so far only mentioned those whose business has been entirely in connection with the sale of apparatus pertaining to the lantern. No less prominent are many whose hobbies are connected with projection, and who, by various teachings and suggestions, have endeavoured to bring the lantern to a higher state of perfection. For several years past our readers will have become acquainted with the articles which have been contributed from the pen of Mr. C. E. Rendle, and when one reads an article, there is often a strong wish to mentally picture what sort of looking party the writer may be. In Mr. Rendle’s case they will now be able to ' gatisfy any curiosity they may have, as we here reproduce a recent portrait of him. When asked when he first began to take an interest in the lantern, he at once confessed to us that he really could not say, he seemed to have been taking a keen interest in it as far | back as he could remember. ‘And as to | photography,” he said, “ it was on my thirteenth