But something in the nature of solution to the riddle was nearer than he had supposed. It came in the man's words which were added in further reply to his father.
"I have no fear but my invention will do these things," he said with strong conviction. "But," he added almost sombrely, "I have other fears."
"Others?"
The commercial mind of Sir Andrew was sharply suspicious.
"Yes."
Again came that troubled movement of the hand across the forehead. The man hesitated in a painful, embarrassed way. Then, with a perfectly helpless gesture, he blurted out something of that which Ruxton had been waiting for.
"Yes, yes," he cried, his eyes full of a passionate light. "I have fears, other fears. Nor are they idle. Nor are they to be belittled. I came here in secret. No one but my two confidential men, who brought this model, know of my coming. No one knows my whereabouts at all, but you, and those two men whom I can trust—even with my life. Fears. My God, if you only knew. I tell you there are people in the world, if they knew of my visit to you, if they saw that model lying on your table, who would not rest until my life was forfeited, and the utility of my invention to this country was destroyed forever."
The man stood up. His great height was drawn up to its uttermost. He was breathing hard, but the light in his eyes was not of the fear of which he spoke. They were burning with a strained defiance of that threat he knew to be hanging over him.
The others rose from their chairs simultaneously. Both were startled. But Sir Andrew far more than his son. Startlingly as the revelation had come, to Ruxton it was revelation. And now it was he who took the initiative. He leant across the table.
"I think I understand something that has been puzzling me all the evening, Mr.—Smith," he said. "And now that I understand it I am satisfied. You have come to us to-day at great danger to yourself. You are risking everything in the world that we shall have the benefit of your invention. The last thought in your mind is the commercial aspect of this affair. Your real object in coming is your secret for the present. I might even hazard a guess at it. But it is your secret, and one we have no desire to probe. You desire a pledge from us. That is obvious. And for myself I give it freely. Your secret is safe with me—safe as the grave. I shall avail myself of your offer of a trip in your submersible, and, if you will permit me, I shall make my own time for it in the near future. Will you allow me that privilege?"