"Guess that's enough for now." With the words the chief backed away, almost timidly, I thought, from the switchboard, and walked to the cage. For a moment he hesitated, but he entered, and emerged with the sparkling object in his hand. "It's the professor's," I choked, crowding close to him. "How'd you know?" he shot back. "All unset stones look pretty much alike." "I just know," was all I could falter. "You 'just know'." The chief sat down on a stool and regarded me searchingly. "Mr. Thornton, when I started out with you, I thought I was on a wild goose chase or the trail of a confession. You looked exactly like a man who had either committed a serious crime, or was getting over a bad drunk. I feel sure now"--he again regarded the diamond--"that your story was not the product of an alcohol-crazed brain. Come on!" He lurched to his feet, and grasped me by the shoulder. "Come through!" * * * * * Without answering, I wrenched myself free. Over my shoulder I saw one of the policemen at the door. In the hand of the other a revolver suddenly appeared. Good God! I glared in bewilderment from one to another. Was I going mad? Surely this was some awful nightmare! What had I said to make them suspect me of having committed a revolting crime? "Sit down!" The command came from the chief. Mechanically I found a stool, and obeyed him. "Hold your stations, boys, and listen carefully," he ordered his men. Then he turned to me. "Professor Wroxton was a wealthy man without kith or kin?" "Yes." "Do you know the nature of his will?" "Yes." Chilled to the heart, I felt the circumstantial net tightening. "What is its nature?" "This house and an annuity to John and his wife," I explained. "The residue of his wealth to me." "Humph!" The chief stared at me piercingly. "And how has business been with you lately?" Damn the man! What right had he to put me through the third degree? I felt my state of dazed horror slowly giving way to anger. I glanced around. The pistol still menaced; the man at the door had not moved. It was useless to try and evade the questions. "For the past year," I replied, "business has been very poor. In fact, the professor advanced me some money." "Humph!" Again that irritating, non-committal grunt. * * * * * The chief turned in his seat and stared thoughtfully at the crystalline cage. "And you don't know what the professor was trying to invent?" "Only its nature," I began. "Ah! That's better. Why didn't you tell me that before?" The chief leaned forward. "Well," I explained, "the whole thing seems so absurd. When the professor told me how his married life had been broken up, he told me that at that time he reached the utmost depths of human suffering. Absolute zero, he called it." "Ah!"