But for all his understanding he had no intention of accepting his own reading without proof from the only direction in which proof could come.

"And what is the commercial aspect of the matter--between us?" he enquired in his most businesslike tone.

Mr. Smith looked up in a startled way from the deep reverie into which his own words had plunged him.

"Commercial?" he echoed a little helplessly.

"Yes." Ruxton smiled. "The--price."

Mr. Smith nodded readily and smiled back. But his reply carried no conviction.

"Yes, yes," he said hurriedly. "I was thinking. Of course--yes. The price."

His infantile manner brought a smile to the shrewd face of Sir Andrew.

Ruxton only waited.

"I--had forgotten," Mr. Smith went on. Then, with his curious tenacious hands clasped about one knee, a hopeless sort of distress slowly filled his eyes. "It--it is difficult," he stumbled. Then quite suddenly a world of relief seemed to come to him. "Would it not be better to leave terms until you have seen, and proved for yourselves, of what my constructed vessel is capable? You see, any price I could name now would sound--er--excessive."

The manner of this strange creature was so delightfully naive that even the keen Yorkshire features of Sir Andrew were reduced to a smile of enjoyment.

"That's the way I like to hear an inventor talk, Mr. Smith," he cried heartily. "Most of 'em want large sums in options on the bare model and registered patents. If your invention--the constructed vessel is capable of what you claim for it, it is worth--millions."

But the millionaire's encouragement seemed to have an adverse effect upon the inventor. Trouble crept again into his eyes, and he pa.s.sed one thin hand across his splendid forehead.

"If it serves to save innocent lives in the future, sir, it has done all that I ask of it," he said at last. "Its value to me then could never be reckoned in millions. There would not be enough cyphers in the mind of man to express that value."

To Ruxton the riddle of this man was growing in obscurity. For all his understanding Mr. Smith's att.i.tude demanded explanation which as yet he was unable to give it.

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, embarra.s.sed 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 pa.s.sionate 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 G.o.d, 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?"

The inventor impulsively held out his hand, and his relief was obvious and intense. It was almost as if he had feared the result of his revelation.

"Your wishes are entirely mine," he said, as Ruxton wrung his hand. "It was this necessity for secrecy which has troubled me. I did not think you would accept it. And--I feared the shattering of all my hopes." He turned to Sir Andrew, who stood watching the scene wonderingly.

"And you, sir?" he asked, with extended hand. "Have I your word?"

"Absolutely, sir."

The bluff tone, and the grip of the Yorkshire hand, had its prompt effect.

"I need no more."

The man proceeded to close up his model.

"And for communicating with you?" demanded Ruxton.

Mr. Smith looked up.

"The same address. Veevee, London. It will always find me."

"Thank you."

Two hours later Ruxton and his father were alone in the library. The inventor had gone, and his precious model had been carefully removed by the two men who had conveyed it to Dorby Towers. For those two hours Sir Andrew and his son had thrashed threadbare the situation created by the stranger's coming. And, incredible as it seemed, in the minds of both men was a steady conviction that the work of that evening was to mark an epoch in the history of their country.

The possibilities were of a staggering nature. Neither could probe the future under this new aspect. If this new principle of ocean traffic were to---- But it was "if." If the man were honest. If the invention were right. If--if, and again--if. That was it. And so they had talked it out.

Now it was time to seek that rest which Ruxton sorely needed. His had been a strenuous day, and he knew he must return to town to-morrow. He rose and stretched himself.

"Well, Dad, it's bed for me," he said, in the midst of a yawn.

His father looked up from his final cigar, which was poised in his hand.

"Yes. You must be tired, boy. There's one thing, though, about that man, that's occurred to me," he added, his mind still dwelling on the subject of their long discussion. "Did you notice his speech? He didn't sound to me English, and yet there--was no real accent."

Ruxton laughed.

"I wondered if that had escaped you." Then his eyes grew serious. "No, he isn't an Englishman. He isn't even Dutch. That I am sure of. But his nationality--no, I cannot say."

"No. It's a difficult matter with these foreigners."

"Yes. But if I can't locate his nationality I am certain of a very important fact."

"And that is?"

"He belongs to--Germany."