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projection arc lamp is identical for amperages ranging from 45-120 direct current.
The Simplex Sun-Light Arc high intensity projection lamp operates successfully with the following standard carbon:
Combination Lamp
Amperage Rating
Direct Current
Columbia Positive Carbon Size
Columbia Negative Size Silvertips
85-120 Amps. 75 85 Amps.
13.6 m/mX 18' 'Cored 11 m/mX 18" Cored
3/8X6" Cored Silvertips 11/32X6" Cored Silvertips
The best operating results and highest efficiency with the 13.6 m/m cored positive and 3/8 X 6 cored silvertip negative in the Simplex Sun-Light Arc lamp is obtained when operating lamp at from 105-110 amperes direct current.
While the 75-ampere Simplex Sun-Light high intensity lamp has just recently been made a commercial proposition there is no question but what this lamp will operate at its highest efficiency with the 11 m/m trim recommended, when using in neighborhood of 80 amperes direct current. The carbon question for these lamps has passed the experimental stage in America. The National Carbon Company, Inc., through their engineers and research staff have perfected and developed the combinations submitted in this report, which have been accepted as standard trims by the General Electric Company, and Sun-Light Arc Corp. makers of the present marketed high intensity projection arc lamps.
New Projection Lamps
A new projection lamp has been developed for 110 to 120 volt service, 250-watt in a T-14 bulb and placed on the market April 1st. This now gives a range available in tubular bulbs from 250 to 1000 watts for standard lighting circuits. In these bulbs are incorporated the latest features of design including the use of the small bulb and the employment of the monoplane filament construction, which latter is also used in the 28 to 32-volt, 300 to 900watt sizes, and the 110-120 volt lamps of 400 watts and below.
Motion Picture Screens
The Multi-Power Screen is made by indenting the surface of highly polished metal sheets. The indentations or "elements" are shallow, of mathematical curvature and degree, and uniformly distributed over the surface. The function of each element is to reflect the minute spot of picture light received upon it to a viewing area of given shape and size, the effect of the screen as a whole being equivalent to the combined effect of all the elements. The principle is analagous to that of a searchlight in that the intensity of the reflected light is governable by varying the angles of curvature — hence the dispersion of the element. Surfaces provided with 10 to 120 elements per sq. in. and of a brightness 6 to 50 times that of plaster have been produced; these were, however, built for outdoor advertising work and are unsuited for close viewing. A machine now nearing
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