HAT in the world could have happened? William had reached the stage now where he was ready to accept anything as a matter of course. He had just passed through so many strange experiences, each more wonderful than the last, that he would hardly have been surprised if Aladdin's genie had appeared to him and asked his commands.

His natural good sense, however, soon reacted against these impressions, for he knew that all the astonishing manifestations which he had met with must be due to natural causes. But what natural cause could explain the danger-signal which had reached him, or the violent shock which he had just experienced?

He saw only two ways in which a shock might reach him in the car; the first was the necessary