Page:The achievements of Luther Trant - Balmer and MacHarg - 1910.djvu/385

Rh feel it at all—moves that mirror and swings the reflected light upon the screen according to the amount of current coming through me. As you see now, the light stays almost steady in the center of the screen, because the amount of current coming through me is very slight, as I am not under any stress or emotion of any sort. But if I were confronted suddenly with an object to arouse fear—if, for instance, it reminded me of a crime I was trying to conceal—I might be able to control every other evidence of my fright, but I could not control the involuntary sweating of my glands and the automatic changes in the blood pressure which allow the electric current to flow more freely through me. The light would then register immediately the amount of my emotion by the distance it swung along the screen. But I will give you a much more perfect demonstration of the instrument," the psychologist concluded, while all three examined it with varying degrees of interest and respect, "during the next half hour while I am making the test that I have planned to determine the murderer of Walter Newberry."

"You mean," cried Siler, "you are going to test the woman?"

"I might have thought it necessary to test Mrs. Newberry," Trant answered, "if the evidence at the house of the presence of a third person who was the murderer had not been so plain as to make any test of her useless."

"Then you—you still stick to that?" Siler demanded derisively.

"Thanks to Mr. Ferris, who is a special agent of the