His thoughts went back to the letter he had received from his father who had died suddenly. Young Atwood had been taking a post-graduate science-medical course in the great Anglo-American University in London. His father's death had brought him hastily back. And the bank had given him the letter which his father had left for him.
"My dear Son:" the letter began. "I am preparing this data for you so that if anything should happen to me before my work is done, you will be able to carry on for me. I haven't been able to tell you—it has had to remain a secret. I have been working with a Dr. Georg Johns, astronomer and physicist of Boston. As you know, all my life, Roy, has been devoted to the discovery of the cause of poliomelitus—"
The dread infantile paralysis. Dr. Atwood, ten years ago, had propounded the theory that it was a sub-microscopic spore so small that even the giant electro-microscopes could not detect it. So small that it was non-filterable—no filter had ever been devised that could trap it, despite the claims of having done that which other medical men had made.
Surely that was a negative result indeed. But, then, Dr. Atwood had discovered, in the ore of Xarium, which existed in very small quantities on Earth, a product which he had named Xarite. He had spent a considerable fortune doing it—the resolution of many tons of Xarium, refined down into an almost microscopic quantity of an electroidally active substance. And with it, for a year he worked miracles. As though by magic the emanations from his tiny Xarite tube, magnified and projected in the fashion of radiotherapy treatments, had cured victims of the dread disease.
But the triumph was short-lived. The Xarite tube exhausted itself. And on Earth, the scarcity of the ore of Xarium was such that to secure another grain of Xarite seemed practically an impossibility. And then the death of Dr. Atwood had come, and Roy had gotten the letter. His father had secretly been working with Dr. Johns. Together, with Dr. Johns' huge electro-spectroscope, they had discovered the existence of Xarite on Planetoid 150. And had kept it secret. With the era of Interplanetary adventure now at hand, both the physicians feared that the Xarite treasure might fall into unscrupulous hands, be exploited for profit. They wanted to get it themselves and invent the radiotherapy projectors suitable for its use; and give it all to the suffering children of the world as their benefaction.
Dr. Atwood's letter to his son told how, finally, Dr. Johns had secured a small spaceship and had gone, trying to get to Planetoid-150. Dr. Atwood, in delicate health, had not dared make the trip. He had been waiting; and had left this letter to Roy, with voluminous data, as a precaution. Roy had read the letter a hundred times. It was in the small spaceship which he had built with the money inherited from his father, and which had brought him here. He remembered its final, pleading words:
"You must carry on for me, Roy. Believe me, son, the lives of thousands of thousands of children will be in your hands. And the health of thousands upon thousands of others, who do not die, but live with twisted little bodies, tragic, pathetic, piteous monuments to the futility of man's medical skill. You have seen them. They will be counting upon you."
How could he fail them? And how could he fail his dead father? The thought of that was what had spurred him; what had brought him here with a grim determination to secure the Xarite and get back as soon as possible.
"You are very quiet," the girl said timidly out of the silence.
"I was thinking," he said. "Out there in our—our God-Heaven if that's what you want to call it—well, it's certainly very queer—"