Seated in the car, which was steadily ascending the great shaft, Roland Clewe took no notice of anything about him. He did not look at the brilliantly lighted interior of the shaft, he paid no attention to his instruments, he did not consult his watch, nor glance at the dial which indicated the distance he had travelled. Several times the telephone bell rang, and Bryce inquired how he was getting along; but these questions he answered as briefly as possible, and sat looking down at his knees and seeing nothing.

When he was half-way up, he suddenly became conscious that he was very hungry. He hurriedly ate some sandwiches and drank some water, and then, again, he gave himself up entirely to mental labor. When, at last, the noise of machinery above him and the sound of voices aroused him from his abstraction, the car emerged upon the surface of the earth, Clewe hastily slid back the door and stepped out. At that instant he felt himself encircled by a pair of arms. Bryce was near by, and there were other men by the engines, but the owner of those arms thought nothing of this.

“Margaret!” cried Clewe, “how came you here?”

“I have been here all the time,” she exclaimed; “or, at least, nearly all the time.” And as she spoke she drew back and looked at him, her eyes full of happy tears. “Mr. Bryce telegraphed to me the instant he knew you were going down, and I was here before you had descended half-way.”

“What!” he cried. “And all those messages came from you?”

“Nearly all,” she answered. “But tell me, Roland—tell me; have you been successful? What have you discovered?”

“I am successful,” he answered. “I have discovered everything!”

Mr. Bryce came forward.

“I will speak to you all very soon,” said Clewe. “I can't tell you anything now. Margaret, let us go. I shall want to talk to you directly, but not until I have been to my office. I will meet you at your house in a very few minutes.” And with that he left the building and fairly ran to his office.

A quarter of an hour later Roland entered Margaret's library, where she sat awaiting him. He carefully closed the doors and windows. They sat side by side upon the sofa.

“Now, Roland,” she said, “I cannot wait one second longer. What is it that you have discovered?”

“Margaret,” said he, “I am afraid you will have to wait a good many seconds. If I were to tell you directly what I have discovered, you would not understand it. I am the possessor of wonderful facts, but I believe also that I am the master of a theory more wonderful. The facts I found out when I got to the bottom of the shaft, but the theory I worked out coming up.”

“But give them to me quickly!” she cried. “The facts first—I can wait for the theory.”

“No,” he said, “I cannot do it; I must tell you the whole thing as I have it, arranged in my mind. Now, in the first place, you must understand that this earth was once a comet.”

“Oh, bother your astronomy, I really can't understand it! What did you find in the bottom of that hole?”

“You must listen to me,” he said. “You cannot comprehend a thing I say if I do not give it to you in the proper order. There have been a great many theories about comets, but there is only one of them in which I have placed any belief. You know that as a comet passes around the sun, its tail is always pointed away from the sun, so that no matter how rapidly the head shall be moving in its orbit, the end of the tail—in order to keep its position—must move with a rapidity impossible to conceive. If this tail were composed of nebulous mist, or anything of that sort, it could not keep its position. There is only one theory which could account for this position, and that is that the head of a comet is a lens and the tail is light. The light of the sun passes through the lens and streams out into space, forming the tail, which does not follow the comet in the inconceivable manner generally supposed, but is constantly renewed, always, of course; stretching away from the sun!”

“Oh, dear!” ejaculated Margaret. “I have read that.”

“A little patience,” he said. “When I arrived at the bottom of the shaft, I found myself in a cleft, I know not how large, made in a vast mass of transparent substance, hard as the hardest rock and transparent as air in the light of my electric lamps. My shell rested securely upon this substance. I walked upon it. It seemed as if I could see miles below me. In my opinion, Margaret, that substance was once the head of a comet.”

“What is the substance?” she asked, hastily.

“It is a mass of solid diamond!”

Margaret screamed. She could not say one word.

“Yes,” said he, “I believe the whole central portion of the earth is one great diamond. When it was moving about in its orbit as a comet, the light of the sun streamed through this diamond and spread an enormous tail out into space; after a time this nucleus began to burn.”

“Burn!” exclaimed Margaret.

“Yes, the diamond is almost pure carbon; why should it not burn? It burned and burned and burned. Ashes formed upon it and encircled it; still it burned, and when it was entirely covered with its ashes it ceased to be transparent, it ceased to be a comet; it became a planet, and revolved in a different orbit. Still it burned within its covering of ashes, and these gradually changed to rock, to metal, to everything that forms the crust of the earth.”

She gazed upon him, entranced.

“Some parts of this great central mass of carbon burn more fiercely than other parts. Some parts do not burn at all. In volcanic regions the fires rage; where my great shell went down it does not burn at all. Now you have my theory. It is crude and rough, for I have tried to give it to you in as few words as possible.”

“Oh, Roland,” she cried, “it is absurd! Diamond! Why, people will think you are crazy. You must not say such a thing as that to anybody. It is simply impossible that the greater part of this earth should be an enormous diamond.”

“Margaret,” he answered, “nothing is impossible. The central portion of this earth is composed of something; it might just as well be diamond as anything else. In fact, if you consider the matter, it is more likely to be, because diamond is a very original substance. As I have said, it is almost pure carbon. I do not intend to say one word of what I have told you to any one—at least, until the matter has been well considered—but I am not afraid of being thought crazy. Margaret, will you look at these?”

He took from his pocket some shining substances resembling glass. Some of them were flat, some round; the largest was as big as a lemon, others were smaller fragments of various sizes.

“These are pieces of the great diamond which were broken when the shell struck the bottom of the cave in which I found it. I picked them up as I felt my way around this shell, when walking upon what seemed to me like solid air. I thrust them into my pocket, and I would not come to you, Margaret, with this story, until I had gone to my office to find out if these fragments were really diamond. I tested them; their substance is diamond!”

Half dazed, she took the largest piece in her hand.

“Roland,” she whispered, “if this is really a diamond, there is nothing like it known to man!”

“Nothing, indeed,” said he.

She sat staring at the great piece of glowing mineral which lay in her hand. Its surface was irregular; it had many faces; the subdued light from the window gave it the appearance of animated water. He felt it necessary to speak.

“Even these little pieces,” he said, “are most valuable jewels.”

She still sat silent, looking at the glowing object she held.

“You see, these are not like the stones which are found in our diamond-fields,” he said. “Those, most likely, were little, unconsumed bits of the original mass, afterwards gradually forced up from the interior in the same way that many metals and minerals are forced up, and then rounded and dulled by countless ages of grinding and abrasion, due to the action of rocks or water.”

“Roland,” she cried, excitedly, “this is riches beyond imagination! What is common wealth to what you have discovered? Every living being on earth could—”

“Ah, Margaret,” he interrupted, “do not let your thoughts run that way. If my discovery should be put to the use of which you are thinking, it would bring poverty, not wealth, to the world, and not a diamond on earth would be worth more than a common pebble. Everywhere, in civilized countries and in barbaric palaces, people would see their riches vanish before them as if it had been blighted by the touch of an evil magician.”

She trembled. “And these—are they to be valued as common pebbles?”

“Oh no,” said he; “so long as that great shaft is mine, these broken fragments are to us riches far ahead of our wildest imaginations.”

“Roland,” she cried, “are you going down into that shaft for more of them?”

“Never, never, never again,” he said. “What we have here is enough for us, and if I were offered all the good that there is in this world, which money cannot buy, I would never go down into that cleft again. There was one moment when I stood in that cave in which an awful terror shot into my soul which I shall never be able to forget. In the light of my electric lamps, sent through a vast transparent mass, I could see nothing, but I could feel. I put out my foot and I found it was upon a sloping surface. In another instant I might have slid—where? I cannot bear to think of it!”

She threw her arms around him and held him tightly.