“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.”

“Let me understand this,” laughed the prisoner; “you say over a number of words and I answer with other words.  You note the exact moment when you speak your word and the exact moment when I speak mine, then you see how many seconds elapse between the two moments.  Is that it?”

“That’s it, only I have a watch that marks the fifths of a second.  Are you willing to make the test?”

“Suppose I refuse?”

“Why should you refuse if you are innocent?”

“But if I do?”

The magistrate’s face hardened.  “If you refuse to-day I shall know how to force you to my will another day.  Did you ever hear of the third degree, Groener?” he asked sharply.

As the judge became threatening the prisoner’s good nature increased.  “After all,” he said carelessly, “what does it matter?  Go ahead with your little game.  It rather amuses me.”

And, without more difficulty, the test began, Hauteville speaking the prepared words and handling the stop watch while Coquenil, sitting beside him, wrote down the answered words and the precise time intervals.