"Some two or three months ago", I answered. "My work occasions much traveling on my part."
The chief and his men turned again to the cage, talking in undertones. He turned again to me.
"You notice that this thing is built in sections. One of them must be movable. Perhaps—" He paused as his eyes fell upon some wires and tubes that trailed across the floor from underneath the cage to a switchboard fastened to the wall.
"Perhaps," he repeated, "it is worked from that board." He crossed over, stared thoughtfully at the shining levers for some seconds, and moved one slightly. The result was astounding. All four of us stared with unbelieving eyes as slowly, without the faintest sound, a section of one wall slid inwards, as if guided by invisible tracks on floor and ceiling.
"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!"