They had a curiosity to know something about the man. Doctor Bronson questioned the purser and ascertained that he was entered on the passenger-list as Mr. A. of America; but whence he came, or what was his business, no one could tell. He had spoken to but few persons since they left port, and the bulk of his conversation had been devoted to stories like those about the whaling business. In short, he was a riddle no one could make out; and very soon he received from the other passengers the nickname of "The Mystery." Fred suggested that Mystery and Mr. A. were so nearly alike that the one name was as good as the other. While they were discussing him, he returned suddenly and said: "The Captain says there are indications of a water-spout to-morrow; and perhaps we may be destroyed by it." With these words he withdrew, and was not seen any more that evening. Fred wished to know what a water-spout was like, and was promptly set at rest by the Doctor. [Illustration: SHOOTING AT A WATER-SPOUT.] "A water-spout," the latter remarked, "is often seen in the tropics, but rarely in this latitude. The clouds lie quite close to the water, and there appears to be a whirling motion to the latter; then the cloud and the sea beneath it become united by a column of water, and this column is what we call a water-spout. It is generally believed that the water rises, through this spout, from the sea to the clouds, and sailors are fearful of coming near them lest their ships may be deluged and sunk. They usually endeavor to destroy them by firing guns at them, and this was done on board a ship where I was once a passenger. When the ball struck the spout, there was a fall of water sufficient to have sunk us if we had been beneath it, and we all felt thankful that we had escaped the danger." CHAPTER V. ARRIVAL IN JAPAN. The great ship steamed onward, day after day and night after night. There was no storm to break the monotony; no sail showed itself on the horizon; no one left the steamer, and no new-comers appeared; nobody saw fit to quarrel with any one else; and there was not a passenger who showed a disposition to quarrel with his surroundings. Stories were told and songs were sung, to while away the time; and, finally, on the twentieth day, the captain announced that they were approaching land, and the voyage would soon be over. [Illustration: FRANK STUDYING NAVIGATION.] Our young travellers had found a daily interest in the instruments by which a mariner ascertains his ship's position. Frank had gone so far as to borrow the captain's extra copy of "Bowditch's Navigator" and study it at odd intervals, and after a little while he comprehended the uses of the various instruments employed in finding a way over the trackless ocean. He gave Fred a short lecture on the subject, which was something like the following: