ast. As the flash disappeared, Lethbridge, who was watching the
ship through his binoculars, saw a great black patch on the cruiser's
side, exactly where the flash had occurred; and while he was still
wondering what it could mean he became aware that the craft was rapidly
settling by the head. And before he could sufficiently recover from his
astonishment to utter a word, the cruiser's bows sank to a level with
the water, her stern rose high in the air, with the propeller still
spinning round, and in another second she dived forward and disappeared,
with the black flag still fluttering from her main truck.

CHAPTER TWENTY THREE.

A SHIP OF MYSTERY.

"Gone!" gasped Lethbridge, as he turned round and stared with startled
eyes at the other occupants of the pilot-house. "By George! Mildmay,
that was a splendid shot of yours; caught her fair, and tore a gap in
her side as big as a church-door! Those torpedo-shells of yours,
Professor, must be truly frightful things, for a single one of them to
be capable of destroying a ship like that in a moment. How big would
she be, Mildmay?"

"Oh, I don't know; something over four thousand tons, I should say--
hillo! what is the matter? Have we stopped?" exclaimed Mildmay, as the
ship's way suddenly eased up almost with a jerk.

"Yes," said Sir Reginald quietly, "I have stopped her until we can
consider what is the proper thing to be done next. Are we to go on and
speak that liner, or are we to let her go on her way without
communicating?"

"What has the liner herself to say about it?" asked Mildmay, picking up
his glasses from the small table upon which he had laid them down, and
bringing them to bear upon the steamer.

"Yes," he said, "she has stopped, which looks as though she wanted to
speak us. And I see no very particular reason why we should not go
alongside and hear what they have to say about the affair. We need not
tell them very much about ourselves, you know, except that we are the
yacht _Flying Fish_, cruising in these waters for our pleasure and to
test the value of a new principle in shipbuilding. It is just possible
that he may have something of importance to communicate to us."

"Very well," said Sir Reginald, "let us go alongside, then, by all
means."

"In that case," said Mildmay, "I would recommend that the boats be got
up from below. It is not unlikely that the skipper may wish us to go
aboard him, and, if so, it is scarcely worth while to