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34 The Optical Magic Lantern Journal and Photographic Enlarger.
killed and wounded is about the size of the headlights used on American locomotives. It is furnished with a powerful reflector, and the light is produced by the combustion of two magnesium wires. /
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THE photographic societies throughout the country have now commenced their /antern cvenings. These are looked forward to with great interest by the members, who have thus an opportunity of exhibiting their work and receiving friendly criticism upon their transparencies.
The Magic Lantern : Its Construction, Illumination, Optics & Uses.
CHAPTER V.—DISSOLVERS.
Tue production of dissolving views, when these are produced in the most effective way, necessitates the employment of two lanterns, each complete in itself, although it is possible to have the dissolving system embodied in one case, and even worked with one light.
The term aissoluing is adopted from the appearance the pictures present on the screen. Thus the spectator, while examining the subject on the screen, becomes aware that it is getting slightly confused by the gradual appearing of another and different subject on the same disc, which slowly acquires strength and force, while at the same time the previous picture becomes weaker, until at last it disappears entirely—in short, the one view is dissolved into another. This effect is produced in a variety of ways, which we shall presently explain.
* With oil lanterns it is imperative that both lamps be kept burning during the whole of the entertainment. The dissolving effect is produced by means of fans having serrated edges placed in front of the objective. When they were first used for the purpose they were moved to and fro by a rack and pinion, but nowadays this has been greatly simplified, and both fans are attached to one end of a lever, each pointing in an opposite direction, as seen in Fig. 17. When it is desired that the light from both lanterns shall be proJected upon the screen simultaneously, the fans are provided with hinges close to the rod upon which they are fastened, that covering the lens
for the time being swung towards the screen, thus exposing both lights.
As we have said, in the case of oil it is found necessary to keep both lights burning throughout
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Fie. 17.
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the entertainment. Quite different, however, is it when the lime-light is used, for with this, the dissolving effect is produced by lowering the light in the one lantern at the time it is being turned on in the other ; but as it is inconvenicnt to have a series of taps to turn on and off as occasion demands, special combination taps have been dewised to meet this requirement.
_ When the oxy-calciumm or spirit jet is used, the spirit is allowed to burn, and the supply of oxygen only is turned off or lessened. Such a dissolving
Fic. 18.
tap to answer the purpose must have a double branch at the top, so that the oxygen may be diverted from one lantern to the other. A con
venient tap of this nature is shown in Tig. 18. By
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