There was no doubting his distinguished visitor’s sincerity. Robert’s voice was husky as he stammered his appreciation.

“Now, let’s get down to brass tacks,” continued the professor. “This device installed on a large enough scale in the Sphere would make it possible to propel it anywhere in space. The possibilities for research would be virtually boundless. Have you estimated the probable cost of such an apparatus?”

“Often. Even with the aid of improved equipment and sufficient workmen, it would require considerable time and a great expenditure. Fifty thousand dollars is a low estimate—and seven months’ time.”

Professor Palmer looked thoughtful. Though he was known to be comfortably fixed, his total resources did not quite meet this sum. Slave to science though he might be, he hesitated to gamble his entire fortune on a visionary venture that might prove to be impracticable. As to the deficiency, he could get that as a loan or a gift from one or more of his many wealthy friends who had every confidence in him. Should the scheme fail, he would be penniless—possibly friendless.

“Do you believe a flight to another planet and back could be made successfully in the Sphere so equipped?” he asked.

Robert considered carefully. He did, but the professor’s question renewed many doubts. Most of all, he hesitated to involve his would-be benefactor in a disastrous venture.

“I do,” he answered truthfully, at last.

“So do I,” supplemented the professor, stoutly, as if to help convince himself. “Would you be willing to undertake such a journey?” he asked suddenly, fixing his eyes keenly upon his host.

“Yes, sir!” responded Robert quickly.

His prompt reply and evident sincerity convinced Professor Palmer that he was in earnest. The professor had decided. Nothing risked, nothing gained. As for Robert, nine months of trench warfare in France had steeled him against fear of anything except women and the devil.