"Very simple," answered our guest. "You know that cold is merely negative heat, and, if reduced to a point, will act like heat, decreasing in strength as the square of the distance." The old artist chuckled. "I knew it," he said. "Go on." "And do you notice that the reflector in the picture has the elliptical curve, instead of the parabolic of the usual reflectors?" I gasped. In painting that object into the picture I had not thought of curves. In fact, knew nothing of conic sections at the time. "The secondary focus of that reflector," went on Mr. Mayhew, "was about sixty feet away. I had designed it for experimenting with light. In fact, I had invented the searchlight, now in general use, as I have learned by reading up lately. But I have also learned more--that in the fifty years of my darkness the scientific world has not caught up to me. At that time I had not only liquefied the six refractory gases of Clerk Maxwell, but had solidified hydrogen and discovered in advance a gas which I had not named, but which I now find is called helium. I had also succeeded in liquefying this gas." "And in the focus of that reflector?" inquired the old artist, half rising from his chair. "Was a small cup of liquefied helium, on which floated a lump of solid hydrogen. It produced a temperature of nearly two hundred and seventy-three minus centigrade--the absolute zero of space." "And it froze the blood in their veins," commented the artist, reseating himself. "Lucky for me you didn't switch it a little higher." I shivered, and after a few moments of silence I asked: "If I did not read your mind, but delved into the infinite, as you say, why didn't I get this too?" "Didn't have time, my boy. But you may have read the mind of Mr. Mayhew, the subconscious mind of Old Bill--the mind that never sleeps and never forgets, you know, and which retained through the years all that Mr. Mayhew had put into it; for you drew into the reflector the elliptical curve, which Mr. Mayhew conceived, but which never in my life have I considered in conjunction with reflectors." "But you?" I asked again. "Your picture?" "I painted from memory, and, if you will remember, left out the reflector. But Mr. Mayhew had also dipped into the infinite, and discovered what no living brain knew. Mr. Mayhew"--he turned to the still shaky old man--"you have lost, it is true, fifty years of your life. But your remaining years will be full of honor, profit, and ease, for the whole scientific world will rise to do you homage. You are still in advance, for you have not only isolated and liquefied helium, the last of the refractory gases, but you will ultimately solidify it." OVER THE BORDER First, let me introduce myself. I am now an old man, healthy of body and mind--else I could not tell this story--but in late middle life was somewhat feeble-minded. I was an installment collector for a furniture house.