"It not only may have come back, it actually has come back," said Hall. "How can you be sure?" "Because I have been over the track, and know that it leads to a secret apartment directly under the furnace in which Dr. Syx pretends to melt the ore!" For a minute after hearing this avowal I was speechless. "Are you serious?" I asked at length. "Perfectly serious. Run your finger along the rock here. Do you perceive a seam? Two days ago, after seeing what you have just witnessed in the Syx tunnel, I carefully cut out a section of the wall, making an aperture large enough to crawl through, and, when I knew the workmen were asleep, I crept in there and examined both tunnels from end to end. But in solving one mystery I have run myself into another infinitely more perplexing." "How is that?" "Why does Dr. Syx take such elaborate pains to deceive his visitors, and also the government officers? It is now plain that he conducts no mining operations whatever. This mine of his is a gigantic blind. Whenever inspectors or scientific curiosity seekers visit his mill his mute workmen assume the air of being very busy, the cars laden with his so-called 'ore' rumble out of the tunnel, and their contents are ostentatiously poured into the furnace, or appear to be poured into it, really dropping into a receptacle beneath, to be carried back into the mine again. And then the doctor leads his gulled visitors around to the other side of the furnace and shows them the molten metal coming out in streams. Now what does it all mean? That's what I'd like to find out. What's his game? For, mark you, if he doesn't get artemisium from this pretended ore, he gets it from some other source, and right on this spot, too. There is no doubt about that. The whole world is supplied by Syx's furnace, and Syx feeds his furnace with something that comes from his ten acres of Grand Teton rock. What is that something? How does he get it, and where does he hide it? These are the things I should like to find out." "Well," I replied, "I fear I can't help you." "But the difference between you and me," he retorted, "is that you can go to sleep over it, while I shall never get another good night's rest so long as this black mystery remains unsolved." "What will you do?" "I don't know exactly what. But I've got a dim idea which may take shape after a while." Hall was silent for some time; then he suddenly asked: "Did you ever hear of that queer magic-lantern show with which Dr. Syx entertained Mr. Boon and the members of the financial commission in the early days of the artemisium business?" "Yes, I've heard the story, but I don't think it was ever made public. The newspapers never got hold of it." "No, I believe not. Odd thing, wasn't it?" "Why, yes, very odd, but just like the doctor's eccentric ways, though. He's always doing something to astonish somebody, without any apparent earthly reason. But what put you in mind of that?"