Hallberg, Josef Henrik, 1874- · New York city, The Moving picture world · leaf 168
her impractical controlling devices for the direct currentprojector arc. MOTION PICTURE ELECTRICITY 161 Water Type.—-Where a resistance unit of the ordi-nary rheostat type is not available, it is possible to manu-facture for quick use a resistance unit which is composedof a barrel with a metal… … Fig.96 in series with the arc lamp and the other terminal of theline. When such a device is filled with salt water, it willallow current to pass through the circuit. The strengthof current will depend upon the distance between the twometal plates and upon the amount of salt put in the water.Such an…
Motion picture theaters · Electric lighting
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