“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.”