A very good lamp, with high illuminating power, to be used in any lantern, especially with this instrument, can be bought at the paraffin-lamp shops for a small sum. The tin duplex lamp, burning crystal oil, is the best. I should recommend any of my readers who have made, or are about to make, the lantern I have described, to get one of these, instead of making the lamp described with it, as it will give nearly twice the light. An arrangement will of course have to be made at the back for the reflector. If a lamp cannot be got that is low enough for the lantern, you can make the body of it yourself. You can generally get, at these shops, damaged lamps at a small cost. Get one that is damaged only in the body. Unscrew the brass-work, as though you were about to fill it, and put it on one side. Unsolder the brass screw-socket from the reservoir. Now make a square tin box for the new reservoir, covering in the top. The box is to be an inch and a quarter deep, and as large as the lantern will allow. In the top cut a hole to solder the brass screw-socket into. Then screw in the brass wick-carrier and make the clip for the reflector.
If a pair of lanterns are used the light will be proportionately stronger, and a strong light is an important thing with this instrument.
Fig. 9 gives the plan of the top and bottom boards of the instrument for use with a pair of lanterns, and requires no further description.
CHAPTER XXII.--INGENIOUS ADAPTATIONS FOR THE LANTERN.
From Mr. Chasemore’s article on revolving slides for the magic-lantern we borrow the following diagram, as showing very clearly the principle which such slides are constructed (Fig. 1).
Round the slide runs a wooden border half an inch wide and three-eighths of an inch thick. The right-hand part of the slide is wood, the left glass, and the moving part showing towards us is also of glass, and fits into a circular wooden ring that is kept in position as it turns by the two tiny buttons on each side of it. One of these buttons works on the frame, the other is fastened to a piece of wood glued on to the wooden part of the slide. Farther to the right is a small silk reel, into which a handle is fixed, and an endless band from the reel round the circle in the buttons completes the machinery. All this is simple enough, and as it has already been described need not be gone into in detail.