Still, they needed better evidence than their mere beliefs. There was no corpus delicti, for instance. "Gentlemen," said Lambert at last, controlling his emotions with a great effort. "I will admit to you that I am in trepidation and a state of mental torture as to Miss Crawford's fate. You are delaying matters, keeping me from my work." "He thinks about work when the girl he claims he loves has disappeared," said Doherty, in a loud whisper to Phillips. Doherty was one of the sleuths who had been digging in the cellar, and the hard work had made his temper short. "You must help us find Miss Crawford before we can let you alone," said Phillips. "Can't you understand that you are under grave suspicion of having injured her, hidden her away? This is a serious matter, Professor Lambert. Your experiments can wait." "This one cannot," shouted Lambert, shaking his fists. "You are fools!" "Steady now," said Doherty. * * * * * "Perhaps you had better come with us to the district attorney's office," went on Phillips. "There you may come to your senses and realize the futility of trying to cover up your crime--if you have committed one. If you have not, why do you not tell us where Miss Crawford is?" "Because I do not know myself," replied Lambert. "But you can't take me away from here. I beg of you, gentlemen, allow me a little more time. I must have it." Phillips shook his head. "Not unless you tell us logically what has occurred," he said. "Then I must, though I do not think you will comprehend or even believe me. Briefly, it is this: yesterday morning I was working on the final series of experiments with a new type of harmonic overtones plus a new type of sinusoidal current which I had arranged with a series of selenium cells. When I finally threw the switch--remember, I was many weeks preparing the apparatus, and had just put the final touches on early that morning--there was a sound such as never had been heard before by human ears, an indescribable sound, terrifying and mysterious. Also, there was a fierce, devouring verditer blue light, and this came from the plates and studs you see, but so great was its strength that it got out of control and leaped about the room like a live thing. For some moments, while it increased in intensity as I raised the power of the current by means of the switch I held in my hand, I watched and listened in fascination. My instruments had ceased to record, though they are the most delicate ever invented and can handle almost anything which man can even surmise." * * * * * The perspiration was pouring from Lambert's face, as he recounted his story. The detectives listened, comprehending but a little of the meaning of the scientist's words. "What has this to do with Miss Crawford?" asked Doherty impatiently. Phillips held up his hand to silence the other sleuth. "Let him finish," he ordered. "Go on, professor."