There was a flare of light upon the screen, as the operator fussed with the lamp for better lumination. He slowly began to turn the crank, and the criminologist watched the screen with no little excitement. The picture thrown up resembled nothing so much as three endless snakes twisting in the same general rhythm from top to bottom of the frame. The twenty-five duplicates were all joined to the original, so that there was ample opportunity to compare the movements.
“Well, gov'nor, which film was that?” asked the operator.
“Not A—it was B or C!”
“Correct. How'd you guess it? Which is this one?”
As he adjusted another roll of film in the projector, Shirley turned to the manager sitting at his side. “Mr. Harrison, were those snakes all exactly alike?”
“No. They all wriggled in the same direction, at the same time. But little rough angles in some movements and queer curves in others made each individually different.”
“Just what I thought. There goes another.—That is not film A, either!”
“Righto!” confirmed the camera man. As the detailed divergence between the lines became more evident in the repetitions, Shirley slapped his knee.
“Now for the finish. Try reel A.”
This time the three snakey lines moved along in almost identical synchronism. The only difference was that the first was thin, the second heavier, the third the darkest and most ragged of all. The relationship was unmistakable!