The Optical Magic Lantern Journal (July 1900)

The Optical Magic Lantern Journal and Photographic Enlarger. 91 ‘occur ” is the faculty much to be valued in this connection, for the topic of the hour is always & subject in which the great ‘‘B. P.” can take an interest. But among subjects which do not depend upon passing events for their popularity it may be assumed, as a general rule, that those which touch the every-day history of ‘the man in the street” are surest of a good reception. Among such are, say, ‘The Breakfast Table,” telling whence and how from the world over come the. coffee, the bread, the butter, the bacon, the marmalade, which constitute the frugal matutinal repast of the man of moderate means, who is thus, unconsciously, a true cosmopolitan in taste; or, to take another example, “The Evolution of the Bicycle, or Motor Car.’ The earliest history of such essentially modern luxuries as these always supplies a vast amount of amusing matter for both the lecturer and the screen. The old: numbers of illustrated journals and the volumes of encyclopedias will be found to supply wealth of illustration. Then, again, the life histories of ‘such-humble things as a box of matches, a bar of soap, a lump of sugar, a scuttle of coals, are subjects which contain much more than appears on the surface. Nothing is commonplace will we but look at it closely enough. The simplest things—the burning of a candle, for example—are indissolubly linked with the fundamental facts of Nature, of which, indeed, they are but dependent phenomena. Read how Faraday in his lectures on ‘‘The Chemical History of a Candle” made this plain, and never forget a sentence of Professor Huxley’s, which runs as follows :—'*To understand what goes on in his own parish a man must know something of the universe; that the pebble which he kicks aside would not be where it is, and what it is, unless a particular chapter of the earth’s history completed untold ages ago had been exactly what it was.” That is the guiding principle for a lecturer on what is called ‘‘ popular science,” and if he will take the many . admirableexamples of Huxley, Tyndall, Faraday, _ Dr. Andrew Wilson, Lord Kelvin, he will not go far wrong. Hurxley’s lectures on ‘Coral ” and on “Chalk” are in particular models of their kind (see the published series of ‘‘ Manchester Science Lectures’’), Biography alone; or linked with the literary or scientific work of the subject is always good, and by looking out forthcoming centenaries one can ‘“‘intelligently anticipate ” a little. .The topography of the great ones dead ‘is another style of the lecture biographical. Thomas Hardyand Dorset, Rich and Jefferiesund Wiltshire, George Eliot and ;Warwickshire— ° these are examples. But the great difficulty here is the getting of the illustrations. Manner and customs in different lands compared with those in our own is a good safe subject. An example is ‘The Marriage Ceremony at Home and Abroad.” (To be continued.) : (eo ony ACETYLENE GAS PURIFIER. A very neat and portable purifier has been placed on the market by Mr. R. J. Moss, now located at more central acetylene gas — premises, 98, Snow Hill, (and late of 97, Great Hampton Street,) Birmingham. The © purifier stands upright, and is 11 inches high. On the top are two taps, one of which is connected from the generator and the other to the burner, so that the gas entering passes downwards through a chamber filled with purifying material. The interior is ingeniously arranged so as to prevent all chances of short circuiting, and the gas remains, when passing through, a sufficient time in contact with the purifying material to remove those impurities which give rise to both the haze and unpleasant fumes with which many users of generators are well acquainted; the specific gravity of the purified gas remaining practically unaltered. As soon as some of the gas is used a fresh supply from the generator forces the purified gas downwards through certain openings in the bottom of the apparatus into a | species of settling chamber, and thence upwards through a tube also filled with filtering material, and at the extreme end with cotton wool to the outlet. One charge of purifying material is estimated to last for a season with average use, and can be renewed for 1s. 6d.; it being sold at 1s. per lb. For use with small generators, which do not wash the gas at all, Mr. Moss provides a small washer at the side, as the efficiency of purifying material is greatly impaired if the ammonia be not taken out of the gas by washing. Mr. Moss is a hard and conscientious worker in the acetylene cause, and both his opinion and goods of his manufacture can be thoroughly relied upon in every respect.