What most frequently recurred to me was the suggestion of Mr. Ward that perhaps the automobile and the boat which had attracted our attention were in reality one and the same. Very probably, at least, the two machines had been built by the same hand. And beyond doubt, these were similar engines, which generated this remarkable speed, more than doubling the previous records of earth and sea.

"The same inventor!" repeated I.

Evidently this hypothesis had strong grounds. The fact that the two machines had not yet appeared at the same time added weight to the idea. I murmured to myself, "After the mystery of Great Eyrie, comes that of Milwaukee and Boston. Will this new problem be as difficult to solve as was the other?"

I noted idly that this new affair had a general resemblance to the other, since both menaced the security of the general public. To be sure, only the inhabitants of the Blueridge region had been in danger from an eruption or possible earthquake at Great Eyrie. While now, on every road of the United States, or along every league of its coasts and harbors, every inhabitant was in danger from this vehicle or this boat, with its sudden appearance and insane speed.