The Optical Magic Lantern Journal (November 1891)

162 The Optical Magio Lantern Journal and Photographio Enlargor. whereby a lantern slide may be projected upon a table. This method will be found very convenient for sketching, copying purposes, and also for examining slides. Our readers will doubtless find many other uses for this valuable adjunct. ? * Sd THE 4th inst. is the last day for sending lantern slides for the competition (open to the world) in connection with the Newcastle-on-Tyne and Northern Counties Photo Association. The only condition is that the work must not have been shown at any previous exhibition. Six slides only can be received from one exhibitor. These should be sent without delay to Mr. Edgar E. Lee (hon. secretary), 11, Beverley-terrace, Cullercoats, Newcastle-on-Tyne. Two silver medals have been placed at the disposal of the judges. » ” * . WE have received from Miss Moore—whose advertisement appears in this issue—some fine gelatine etchings, copied direct without the aid of photography,both from sketches and reduced from nature. In the latter case the reduction is rendered by means of an instrument termed the philograph, which somewhat resembles a particular form of view-finder. Miss Moore, who is in every sense an artist, considers that this method lends itself to teaching drawing and perspective, and intends imparting particulars in a course of six lessons. 2 2 od THE atrial graphoscope is a new instrument for what is termed “showing lantern slides in the air.’ It consists of a strip of wood such as ts used for making the slats of Venetian blinds; this is painted neutral tint and pivoted at its centre. The arms are rapidly revolved by suitable mechanism and lantern transparencies projected upon the screen which is thus formed by the persistence of vision. al e » Ir one were asked how to show gelatine or celluloid transparencies in a lantern, they would probably say place the gelatine between two glasses, and this isthe method usually employed. Mr. Pumphrey has invented a new frame, which dispenses with the glass supports. The film is placed in a zinc mat, and the edges bent over it; as this, however, does not ensure its being flat, they are then placed ina stamping machine which indents a half round, which not only strengthens the rim, but also serves to stretch the films and render them flat and tight. z IxsTEAD of the papers on various subjects which were read at each meeting of the Lantern Society (20, Hanover-square, W.) last session, | the Council propose to reduce the number of ; papers, and to have, once a month, an informal meeting, at which technical matters in connection with the lantern can be discussed. Members are invited to bring slides with them to these meetings for criticism or discussion, or for the instruction of others. Members are also requested to bring any pieces of apparatus with them for exhibition and discussion. = s * A sHoRT time ago Mr. G. Goodwin Norton gave a highly successful open-air lantern exhibition at Hythe. The disc was 2oft. in diameter, and the lantern was placed in a van 7oft. distant. As it was a moonlight night, it was necessary to turn the jets up to roaring point, but as a military band was also stationed in close proximity, the noise was not noticeable. ® 2 2 From reports received from various quarters we learn that Mr. Stock’s new oil lamp is meeting with great appreciation by those who use it. 202 Zirconia. Some little time ago, when in conversation with _ one of the Professors of a large London institu tion, he informed us that, for class work, he preferred zirconia to lime for the oxy-hydrogen light ; and that, with the former, which was practically indestructible, it was possible (after an exhibition) to set the lantern apparatus away, say, on a shelf, for an unlimited period, and when the gas supply was connected and a light applied at the burner, it was possible to get a light of the same degree of intensity as was obtained at the previous time of using—that is, of course, presuming that the adjustment of the zirconia to the nipple had not been disturbed. Now let us ascertain something about zirconia, which appears to bea valuable substitute for lime cylinders for producing the oxy-hydrogen light. It is just a hundred years ago since the metal zirconium was discovered by Klaproth, in the mineral zircon, which is found in Ceylon, California, and certain parts of Ireland. Jt contains about thirty-three per cent. of silica, and the remaining parts of the earth are mixed with iron. Various methods have been employed for separating the zirconia. One method of removing the silica from the earth is by rendering the zircons red-hot, and then throwing the pieces into water, after which they can be readily powdered. When thoroughly dry, this powder is mixed with certain proportions of carbonate of soda and carbonate of potash, then heated until the mixture fuses,