Huge transatlantic steamers completed the ocean passage in five days. And the engineers had not yet spoken their last word. Neither were the navies of the world behind. The cruisers, the torpedo boats, the torpedo-destroyers, could match the swiftest steamers of the Atlantic and Pacific, or of the Indian trade.

If, however, this were a boat of some new design, there had as yet been no opportunity to observe its form. As to the engines which drove it, they must be of a power far beyond the fastest known. By what force they worked, was equally a problem. Since the boat had no sails, it was not driven by the wind; and since it had no smoke-stack, it was not driven by steam.

At this point in the report, I again paused in my reading and considered the comment I wished to make.

"What are you puzzling over, Strock?" demanded my chief.

"It is this, Mr. Ward; the motive power of this so-called boat must be as tremendous and as unknown as that of the remarkable automobile which has so amazed us all."

"So that is your idea, is it, Strock?"

"Yes, Mr. Ward."

There was but one conclusion to be drawn. If the mysterious chauffeur had disappeared, if he had perished with his machine in Lake Michigan, it was equally important now to win the secret of this no less mysterious navigator. And it must be won before he in his turn plunged into the abyss of the ocean. Was it not the interest of the inventor to disclose his invention? Would not the American government or any other give him any price he chose to ask?

Yet unfortunately, since the inventor of the terrestrial apparition had persisted in preserving his incognito, was it not to be feared that the inventor of the marine apparition would equally preserve his? Even if the first machine still existed, it was no longer heard from; and would not the second, in the same way, after having disclosed its powers, disappear in its turn, without a single trace?

What gave weight to this probability was that since the arrival of this report at Washington twenty-four hours before, the presence of the extraordinary boat hadn't been announced from anywhere along the shore. Neither had it been seen on any other coast. Though, of course, the assertion that it would not reappear at all would have been hazardous, to say the least.

I noted another interesting and possibly important point. It was a singular coincidence which indeed Mr. Ward suggested to me, at the same moment that I was considering it. This was that only after the disappearance of the wonderful automobile had the no less wonderful boat come into view. Moreover, their engines both possessed a most dangerous power of locomotion. If both should go rushing at the same time over the face of the world, the same danger would threaten mankind everywhere, in boats, in vehicles, and on foot. Therefore it was absolutely necessary that the police should in some manner interfere to protect the public ways of travel.

That is what Mr. Ward pointed out to me; and our duty was obvious. But how could we accomplish this task? We discussed the matter for some time; and I was just about to leave when Mr. Ward made one last suggestion.

"Have you not observed, Strock," said he, "that there is a sort of fantastic resemblance between the general appearance of this boat and this automobile?"

"There is something of the sort, Mr. Ward."

"Well, is it not possible that the two are one?"

Chapter 6

THE FIRST LETTER

After leaving Mr. Ward I returned to my home in Long Street. There I had plenty of time to consider this strange case uninterrupted by either wife or children. My household consisted solely of an ancient servant, who having been formerly in the service of my mother, had now continued for fifteen years in mine.

Two months before I had obtained a leave of absence. It had still two weeks to run, unless indeed some unforeseen circumstance interrupted it, some mission which could not be delayed. This leave, as I have shown, had already been interrupted for four days by my exploration of the Great Eyrie.