and, attached to the stern of the vessel by an ingeniously devised ball-and-socket joint in such a manner as to render a rudder unnecessary, was to be seen a huge propeller having four tremendously broad sickle-shaped blades, the palms of which were hollowed in such a manner as to gather in and concentrate the air, or water, about the boss and powerfully project it thence in a direct line with the longitudinal axis of the ship. Crowning the whole there was a low superstructure immediately over and of the same length as the bilge-keels, very much resembling the upper works of a double-bowed vessel such as are some of the small Thames river steamers. This was decked over, and afforded a promenade about two hundred feet long by thirty feet wide. And, lastly, rising from the centre of this deck there was a spacious pilot-house with a dome-like roof, from the interior of which the movements of the vessel could be completely controlled. The entire hull of the vessel, excepting the double-bowed superstructure, was left unpainted, and it shone like a polished mirror. The superstructure, however, was painted a delicate grey tint, with the relief of a massive richly gilded cable moulding all round the shear-strake and the further adornment of a broad ribbon of a rich crimson hue rippling through graceful wreaths of gilded scroll-work at bow and stern, the name Flying Fish being inscribed on the ribbon in gold letters. Altogether, notwithstanding her unusual form, the aerial ship was an exceedingly graceful and elegant object, and, but for her enormous proportions, looked admirably adapted for her work.

Under other circumstances the professor would probably have been seriously offended at the baronet’s incredulous exclamation; but as it was he was so confident of his success—so gratified and triumphant altogether—that he could afford to be not only forgiving but actually tolerant. He therefore replied to Sir Reginald only with a mute smile of amused compassion for the baronet’s lamentable ignorance and unbelief.

The professor’s smile somewhat reassured Sir Reginald, though he still continued to eye his novel possession very dubiously.

“You once spoke of Atlantic liners,” he at last remarked to the professor; “but surely this craft is larger than the largest Atlantic liner afloat. What are her dimensions?”

“She is six hundred feet long, by sixty feet diameter at the point of her greatest girth,” quietly replied the professor.

“And do you mean to tell me that such a monster will ever float in the air?” ejaculated the baronet, his incredulity returning and taking possession of him with tenfold tenacity.

“I do,” answered the professor firmly, his self-love at length becoming slightly ruffled. “In that ship you shall to-night soar higher into the empyrean than mortal has ever soared before; and after that you shall, if you choose, sleep calmly until morning at the bottom of the English Channel. By and by at the dinner-table I will endeavour to demonstrate to you, my dear friend, that it is her immense proportions alone which will enable her to float in so thin a fluid as air.”

“Very well,” said the baronet in the tones of a man still utterly unconvinced; “if you say so, I suppose I must doubt no more. Now, please, introduce to us the novel details of this wonderful craft of yours.”

“With pleasure,” answered the professor, his brow clearing and a gratified smile suffusing his countenance. “A few minutes will suffice to show you all that can be seen from the outside. Those small circular pieces of glass which you perceive let into the hull here and there are, as you have no doubt already surmised, windows to enable us to observe what is passing outside. The larger windows at the bow and stern protect powerful electric lamps, and are exclusively for the purpose of lighting up our surroundings when we are at the bottom of the sea. This,”—pointing to what looked like a circular trap-door in the bottom of the ship, some fifteen feet from the centre on the port side—“is the anchor recess; and this,”—pointing to a corresponding arrangement on the starboard side—“is the door through which we shall obtain egress from and access to the ship when she is at the bottom of the sea.”

“Do you mean by that, that we are going to leave the ship and walk about on the bed of the ocean?” asked the baronet.

“Certainly,” answered the professor with a look of surprise. “Our exploration of the ocean’s bed will probably be one of the most interesting incidents of the expedition.”

The baronet shrugged his shoulders and the professor continued:

“These bilge-keels serve a threefold purpose; they enable the ship to rest steadily and firmly on the ground, as you see, which, from her peculiar form, she could not otherwise do; they also form the sheaths, so to speak, of four anchors to fasten her securely to the ground either above or beneath the water—a most necessary precaution, believe me; and they also add considerably to the cubical contents of the water-chambers, with which they communicate, which will help to sink the ship to the bottom. Lastly, there is the propeller, the only peculiarities of which are its great diameter—fifty feet—its enormous surface area, and the fact that it is attached to the hull in such a way as to admit of its being turned freely in any direction, thus dispensing with all necessity for a rudder.”

“Why have you left the hull unpainted, professor? I suppose you had some good reason for so doing?” remarked the colonel, chiming into the conversation.

“I had no less than three good reasons for leaving the hull of the ship unpainted,” answered the professor. “In the first place, aethereum is quite insensible to the attacks of air and water—it never oxidises, and paint was therefore unnecessary for its preservation. In the next place, the quantity of paint necessary to cover that enormous surface would weigh something considerable; and, as I have throughout the work taken the utmost pains to keep down all the weight to the lowest ounce consistent with absolute safety, I rejected it on that account. And lastly, I take it that we are anxious to avoid all unnecessary observation; and I believe this cannot be better accomplished than by preserving the brilliant metallic lustre of the hull, which, especially when we are floating in mid-air, will reflect the tints of the surrounding atmosphere, and so make it almost impossible to distinguish us.”

“Except when the sun’s rays fall directly upon us, eh, professor?” remarked Mildmay.

“In that case,” returned the professor, “observers will see a dazzling flash of light in which all shape will be indistinguishable.”

“And we shall thus be mistaken for a meteorite,” exclaimed the baronet somewhat sarcastically. “Excellent! admirable! I really must congratulate you, professor, upon the wonderful foresight with which you seem to have provided for every possible and impossible emergency. Now, what is the next marvel?”

“There is nothing more down here. We will now proceed on board, if you please, gentlemen,” said the professor; and he forthwith led the way up a ladder which leaned against the vessel’s lofty side. This conducted them as far as the upper curve of her cylindrical bilge, at which point they encountered a flight of light ornamental openwork steps permanently attached to the ship’s side, up which they passed to the gangway in the stout metal railing which served instead of bulwark, and so reached the spacious promenade deck. Looking down into the yard from this coign of vantage, they seemed to be an enormous height from the ground; and the baronet shrugged his shoulders more 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,”