The Optical Magic Lantern Journal (October 1892)

The Optical Magic Lantern Journal and Photographic Enlarger. 127 projection apparatus, the great thing is to get one point of illumination only in the light, and the automatic, or other adjustments of the carbons are designed to this end. Resistence by coils is necessary or desirable to bring down the current to the minimum, that shall give the desired illumination. Taking the Siemens small size differential lamp as an example, the light is perfectly under control, and the works are contained in a base that occupies little room. It will in fact work with almost any lantern, if the body is raised to suit the length of the carbons, and the base of the lantern is open. For small discs the ‘‘ Focus incandescent lamp”’ is very useful, as a disc of 8 to 12 feet can be obtained with the 100 candle power pattern. The great advantage of this for home use and experimental work, is that once in position and adjusted for centre of optical system of lantern, it is only a question of making the connection with the electric supply, or switching on the current, to get the apparatus ready for use, and project pictures, &c., on the screen. ——:0:— An Amateur Saturator and Jet. No. III. By Cuericus. I now proceed to give particulars of a few modifications which I subsequently made in the jet already described. They principally relate to the gas-chamber, the nipple, and the lime-turning arrangement. Under these three heads I shall deal with them. The rest of the jet remains unaltered, with the exception of what I have called the “ Side-tubes.”’ These, instead of being curved upward as shewn in the last paper, are bent into the form indicated in fig. 1, which gives their appearance, viewed from above, before the other parts of the jet are added. The part z, where the tubes are soldered together, goes into one side of the gas-chamber, and should be long enough to reach through it to the further end. The ends are closed, and a row of small holes drilled in the side of each tube to admit the gases into the chamber. 1. The gas-chamber. This is made up of three parts. The lowest is of brass tube lin., or rather more in diameter, and about 3in. deep. I altered mine into the form of a square. But further thought has convinced me that there is nothing gained by doing so. Whichever form is adopted, the side tubes must be inserted into one side as at a (Fig. 2), and plates of brass cut for the top and bottom of the chamber. c is a piece of brass tube about } in. long, and just large enough to go through the top of the chamber, leaving about $ in. all round. These may all be screwed together, as in the former jet— unless the square form be adopted—in which case of course the top and bottom of the chamber will have to be soldered. Before putting these together, I inserted a piece of gauze, No. 50, beetwen the tubes and the top of the chamber. If this is done, the Fig. 1. tube c may be filled with granulated pumice, and the chamber itself becomes a flame extinctor. The tube dis about 4 in. long, and is made to screw into c. The top of it is closed witha disc through which the tube ¢ passes. I need hardly add that great care must be taken to make all these joints gas-tight. 2. The nipple. The tube e which carries the nipple is of copper, 2 in. diameter, and should be solid-drawn. It is bent, as shewn in the figure, enough to make the nipple deliver the gas upon the lime at the proper angle, 7.c., about 40° from the perpendicular to the surface of the lime. The nipple itself, f, is made of brass rod or stout wire, large enough to screw into ec. I first cut the screw upon one end for about 3 of an in., and then cut off a length of about in., of which, of course, + in. was screwed, and 2 plain. Fixing this in the lathe, and beginning from the screwed end, I drilled this almost through, Fig, 3. Fig. 2 leaving something less than} of an inch. This was done with as large a drill as the rod would bear. Then with a Jine drill, inade of part of a kuitting-needle, [ drilled the remaining portion by hand, and then filed the plain part of the outside into shape. I made two or three of these nipples, with holes at the point of different