I knew Hall was not the person to make such a remark carelessly, and my curiosity was intensely excited, but, knowing his peculiarities, I did not press him for an explanation. When we arrived at the head of the tunnel I was surprised at finding no workmen there. "I stopped blasting some time ago," said Hall, in explanation, "for a reason which, I hope, will become evident to you very soon. Lately I have been boring very slowly, and yesterday I paid off the men and dismissed them with the announcement, which, I am confident, President Boon will sanction after he hears my report of this morning's work, that the tunnel is abandoned. You see, I am now using a drill which I can manage without assistance. I believe the work is almost completed, and I want you to witness the end of it." He then carefully applied the drill, which noiselessly screwed its nose into the rock. When it had sunk to a depth of a few inches he withdrew it, and, taking a hand-drill capable of making a hole not more than an eighth of an inch in diameter, cautiously began boring in the centre of the larger cavity. He had made hardly a hundred turns of the handle when the drill shot through the rock! A gratified smile illuminated his features, and he said in a suppressed voice: "Don't be alarmed; I'm going to put out the light." Instantly we were in complete darkness, but being close at Hall's side I could detect his movements. He pulled out the drill, and for half a minute remained motionless as if listening. There was no sound. "I must enlarge the opening," he whispered, and immediately the faint grating of a sharp tool cutting through the rock informed me of his progress. "There," at last he said, "I think that will do; now for a look." I could tell that he had placed his eye at the hole and was gazing with breathless attention. Presently he pulled my sleeve. "Put your eye here," he whispered, pushing me into the proper position for looking through the hole. At first I could discern nothing except a smoky blue glow. But soon my vision cleared a little, and then I perceived that I was gazing into a narrow tunnel which met ours directly end to end. Glancing along the axis of this gallery I saw, some two hundred yards away, a faint light which evidently indicated the mouth of the tunnel. At the end where we had met it the mysterious tunnel was considerably widened at one side, as if the excavators had started to change direction and then abandoned the work, and in this elbow I could just see the outlines of two or three flat cars loaded with broken stone, while a heap of the same material lay near them. Through the centre of the tunnel ran a railway track. "Do you know what you are looking at?" asked Hall in my ear. "I begin to suspect," I replied, "that you have accidentally run into Dr. Syx's mine." "If Dr. Syx had been on his guard this accident wouldn't have happened," replied Hall, with an almost inaudible chuckle.