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Quipment Center in New York were generously put at the disposal of the Committee for the test. Two arc projectors, similar in all respects, were arranged to throw two pictures, side by side, on a single white beaded screen, and the optience (from 5 to 8 in number) sat in the line between the two pictures. Both arcs were maintained, as nearly as possible, at 60 amperes and 50 volts throughout the tests. To each person were given slips of papers having spaces for checking his preference of the two pictures on the screen in respect to brightness, clearness and contrast. With light beams intercepted, the untinted loop of film was put in one machine and a tinted loop in the other. The room lights were turned off and then the two pictures thrown on the screen. It was originally planned for each observer to note his first impression of the relative brightness, clearness and contrast of the two pictures and then after examining the pictures for two minutes, to note again in separate columns his final decision. It was found, however, that it took so long to form any definite opinion that the pictures were run for one-half minute and judged on the final decision alone. After this halfminute run, the light beams were cut off and the room lights turned on in order that the eyes of the optience might regain their original sensitiveness.
A thin metal disc, having holes all over it ^ inch between centers, and of such a size that just one-half of the disc area was cut away (i. e.,, hole .2 inch in diameter) was placed in the front of the objective throwing the untinted picture. A second test was now made and judged as before. Then a third with a disc having one-quarter of its area cut away (.141 inch holes), and a fourth with one-eighth (.1 inch holes) cut away. These discs, of course, reduced the quantity of light from the untinted film to one-half, onequarter and one-eighth of its original value respectively, while the tinted picture remained unchanged.
The results of tnese tests are given in the table. Only a decided majority of votes was considered as an indication of difference. It was quite astonishing, however, to find how closely the opinions coincided in the great majority of cases. The colors tried were:
Pale rose, pale carmine, deep red and deep carmine.
Pale amber, pale yellow, pale lemon, lemon and deep amber.
Very pale green, pale blue green, pale olive, grass green and deep green.
Pale blue, blue, deep blue, red blue, very red blue, deep purple and deep violet.
Perhaps the most striking thing shown by the table is that the pale yellow and pale green give the appearance of equal or greater brightness, though, of course, having less energy delivered to the screen by the amount absorbed in the dye on the film. This effect was so marked that in the case of the pale amber, the films and machines were interchanged with results that checked with the previous test. Of equal interest is the fact that the contrast was invariably increased by pale colors, and the clearness as well, with the exception of pale blue, pale blue green, pale olive and pale car
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