But almost instantly Groener had become calm again. "I beg your pardon," he said, "I'm a little on my nerves. I'll behave myself now, I'm ready for those things you spoke of that are not so amusing."

      "That's better," approved Hauteville, but Coquenil, watching the prisoner, shook his head doubtfully. There was something in this man's mind that they did not understand.

      "Groener," demanded the magistrate impressively, "do you still deny any connection with this crime or any knowledge concerning it?"

      "I do," answered the accused.

      "As I said before, I think you are lying, I believe you killed Martinez, but it's possible I am mistaken. I was mistaken in my first impression about Kittredge—the evidence seemed strong against him, and I should certainly have committed him for trial had it not been for the remarkable work on the case done by M. Coquenil."

      "I realize that," replied Groener with a swift and evil glance at the detective, "but even M. Coquenil might make a mistake."

      Back of the quiet-spoken words M. Paul felt a controlled rage and a violence of hatred that made him mutter to himself: "It's just as well this fellow is where he can't do any more harm!"

      "I warned you," pursued the judge, "that we are coming to an unpleasant part of this examination. It is unpleasant because it forces a guilty person to betray himself and reveal more or less of the truth that he tries to hide."

      The prisoner looked up incredulously. "You say it forces him to betray himself?"

      "That's practically what it does. There may be men strong enough and self-controlled enough to resist but we haven't found such a person yet. It's true the system is quite recently devised, it hasn't been thoroughly tested, but so far we have had wonderful results and—it's just the thing for your case."

      Groener was listening carefully. "Why?"

      "Because, if you are guilty, we shall know it, and can go on confidently looking for certain links now missing in the chain of evidence against you. On the other hand, if you are innocent, we shall know that, too, and—if you are innocent, Groener, here is your chance to prove it."

      If the prisoner's fear was stirred he did not show it, for he answered mockingly: "How convenient! I suppose you have a scales that registers innocent or guilty when the accused stands on it?"

      Hauteville shook his head. "It's simpler than that. We make the accused register his own guilt or his own innocence with his own words."

      "Whether he wishes to or not?"

      The other nodded grimly. "Within certain limits—yes."

      "How?"

      The judge opened a leather portfolio and selected several sheets of paper ruled in squares. Then he took out his watch.

      "On these sheets," he explained, "M. Coquenil and I have written down about a hundred words, simple, everyday words, most of them, such as 'house,' 'music,' 'tree,' 'baby,' that have no particular significance; among these words, however, we have introduced thirty that have some association with this crime, words like 'Ansonia,' 'billiards,' 'pistol.' Do you understand?"

      "Yes."

      "I shall speak these words slowly, one by one, and when I speak a word I want you to speak another word that my word suggests. For example, if I say 'tree,' you might say 'garden,' if I say 'house,' you might say 'chair.' Of course you are free to say any word you please, but you will find yourself irresistibly drawn toward certain ones according as you are innocent or guilty.

      "For instance, Martinez, the Spaniard, was widely known as a billiard player. Now, if I should say 'billiard player,' and you had no personal feeling about Martinez, you might easily, by association of ideas, say 'Spaniard'; but, if you had killed Martinez and wished to conceal your crime then, when I said 'billiard player' you would not say 'Spaniard,' but would choose some innocent word like table or chalk. That is a crude illustration, but it may give you the idea."

      "And is that all?" asked Groener, in evident relief.

      "No, there is also the time taken in choosing a word. If I say 'pen' or 'umbrella' it may take you three quarters of a second to answer 'ink' or 'rain,' while it may take another man whose mind acts slowly a second and a quarter or even more for his reply; each person has his or her average time for the thought process, some longer, some shorter. But that time process is always lengthened after one of the critical or emotional words, I mean if the person is guilty. Thus, if I say, 'Ansonia' to you, and you are the murderer of Martinez, it will take you one or two or three seconds longer to decide upon a safe answering word than it would have taken if you were not the murderer and spoke the first word that came to your tongue. Do you see?"

      "I see," shrugged the prisoner, "but—after all, it's only an experiment, it never would carry weight in a court of law."

      "Never is a long time," said the judge. "Wait ten years. We have a wonderful mental microscope here and the world will learn to use it. I use it now, and I happen to be in charge of this investigation."

      Groener was silent, his fine dark eyes fixed keenly on the judge.

      "Do you really think," he asked presently, while the old patronizing smile flickered about his mouth, "that if I were guilty of this crime I could not make these answers without betraying myself?"

      "I'm sure you could not."

      "Then if I stood the test you would believe me innocent?"

      The magistrate reflected a moment. "I should be forced to believe one of two things," he said; "either that you are innocent or that you are a man of extraordinary mental power. I don't believe the latter so—yes, I should think you innocent."