Wondering, uneasy, nervous, the men gathered about at our orders. Skeptically, with no confidence whatever, I unstopped the bamboo and pointed the open end at the massive masonry wall. I uttered an involuntary ejaculation of wonder. Azcopil started and leaped back. Before us a large circular area of the rock glowed with brilliant red light! It was as if I held a powerful electric flashlight with a red bulb in my hand, yet no light, no rays streamed from the uncanny thing. Deep sighs of wonder came from the awed soldiers as, still wondering, I moved it back and forth, up and down, searching the stonework for signs of a door. Every detail of the wall was clearly illuminated. Of course, that was what Nohul Voh had meant. The thing would give us light to find the door. He loved to surround everything with mystery. But there was nothing so very mysterious about the invention after all. It was probably some radium compound--he had warned me it would burn flesh--but if so, how could bamboo protect me? Perhaps it was some other substance, something unknown to the rest of the world. Well, in that case, it was most interesting--would be a priceless thing if it could be commercialized. But, after all, as far as finding the door was concerned, it was no better than an ordinary torch. Such thoughts ran through my brain, as anxiously, impatiently I went slowly, carefully over the stonework with the prince beside me, for after the first surprise he had no further fear of the seemingly magic light. Suddenly he sprang forward. Under the glare from the tube a beautiful bas-relief was clearly outlined, glowing as readily as though carved on the surface of a gigantic ruby. It was an enormous thing, sculptured on the faces of a dozen great stone blocks so well joined that the cement-filled seams were scarcely visible. All this I took in at a glance. Then I saw what had attracted the prince. As sharp and clear, as though painted in black pigment upon the stones, was the outline of a rectangle! “Itzimin, look, the door!” ejaculated the prince.