that are at the bottom of his insanity. Those words which are connected with the trouble cause deeper feeling in the subject and are marked by longer intervals of time before the word in reply can be spoken. The nature of the word spoken by the patient often clears the causes for his mental agitation or prostration.
"In this case, if Margaret Lawrie had reason to believe that any one of you were closely associated with her father's trouble, the speaking of that one's name or the mentioning of anything connected with that one, must betray an easily registered and decidedly measurable disturbance."
"I have heard of this," Joslyn commented.
"Excellent," the president of the trustees agreed, "if Margaret's physician does not object."
"I have already spoken with him," Trant replied. "Can I expect you all at Dr. Lawrie's to-morrow morning when I test Margaret to discover the identity of the intimate friend who caused the crime charged to her father?"
Dr. Lawrie's three dearest friends nodded in turn.
Trant came early the next morning to the dead treasurer's house to set up the chronoscope in the spare bedroom next to Margaret Lawrie's.
The instrument he had decided to use was the pendulum chronoscope, as adapted by Professor Fitz of Harvard University. It somewhat resembled a brass dumb-bell very delicately poised upon an axle so that the lower part, which was heavier, could swing slowly back and forth like a pendulum. A light, sharp pointer paralleled this pendulum. The weight, when
