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Lumière projector |
 The early Lumière projector was very interesting. Realising the high inflammability of the celluloid film, and the intense heat produced by the focusing of the electric arc light through the condenser upon the film, the experimenters sought to remove the danger of fire by counteracting the heat production of the rays of light. A spherical bottle, filled with water, was placed between the electric arc and the lens to act as condenser, Fig 4. The bottle B was encased in a metal cylinder E, fixed to the front of the lantern A by four rods, each terminating in a screw V. The metal cylinder E was continued forwards in the form of a tube F, the end of which was fitted with a hinged shutter G carrying a small piece of ground glass H. When film was set in motion this hinged shutter was lifted and laid back upon the top of the tube to which it was attached. The spherical bottle, which was filled with distilled water to which a few drops of acetic acid were added, acted in exactly the same way as the glass condenser of to-day. But it possessed this advantage. The luminous rays were concentrated, and there was no loss of luminous light; only the heat rays were absorbed almost entirely by the water. Another beneficial result was that the light thrown through the picture, and thence on the screen, was whiter, because the condenser glass is greenish, and imparts that tint to the light passing through it. In the course of about 30 or 40 minutes the water under the action of the heat rays commenced to boil, but no inconvenience resulted. A piece of coke, D, attached to a short length of wire C, was suspended in the decanter and placed just below the surface of the water, thus causing it to boil with complete evenness; there was no spurting of the contents, and no bubbling to interfere with the light. If the sphere of water were removed or broken during the operation of the lantern, as the condensation of the light rays immediately ceased there was no danger of the film being set alight. Source: Moving Pictures - How they are made and worked, |