re expressively than ever as he glanced
first below and then around him, realising more fully than ever, as he
did so, the immense proportions of his new possession. He said nothing,
however, but turned inquiringly to the professor.

"This way, gentlemen, if you please," said the German, in answer to the
look; and he led them aft to what may be styled the quarter-deck.

"You spoke about the weight of a coat of paint on the hull just now, but
I see you have planked the deck. The weight of all this planking must
be something considerable," remarked Mildmay.

"A mere trifle; it is only a thin veneering just to give a secure and
comfortable foothold," remarked the professor. He paused at what looked
like a trap-door in the deck and said:

"We shall not be always soaring in the air nor groping about at the
bottom of the sea; we shall sometimes be riding on the surface; and I
have therefore thought it advisable to provide a couple of boats. Here
is one of them."

He stooped down, seized hold of and turned a ring in the flap, and
raised the trap-door, disclosing a dark pit-like recess of considerable
dimensions. Letting the flap fold back flat on the deck, the professor
then stooped down and grasped the handle of a horizontal lever which lay
just below the level of the deck, and drew it up into a perpendicular
position, and, as he did so, a pair of davits, the upper portions of
which had been plainly visible, rose through the aperture close to the
protecting railing, bringing with them a handsomely modelled boat
hanging from the tackles. The professor deftly turned the davits
outward, and there hung the boat at the quarter in the exact position
she would have occupied in an ordinary ship.

"Bravo, professor; very clever indeed!" exclaimed Mildmay. "But what is
the object of those four curved tubes projecting through the boat's
bottom?"

"Those tubes," answered the professor, "are the boat's means of
propulsion. You see," he explained, "being built of aethereum, the boat
is extremely light, and draws so little water that a screw propeller
would be quite useless to her. So I have substituted those tubes
instead. One pair, you will observe, points toward the stern, and one
pair toward the bow. The boat's engine is a powerful three-cylinder
pump, and it sucks the water strongly in through the tubes which point
forward, discharging it as powerfully out through those which point
astern; thus drawing and driving th