Square in front of the fire, dreamily puffing at his cigar and apparently studying the merits of a painting hanging behind him, and on the reflected image of which in the mirror before him his eyes lazily rested, sat Cyril Lethbridge, ex-colonel of the Royal Engineers, a successful gold-seeker, and almost everything else to which a spice of adventure could possibly attach itself. And next him again, on the side of the fire-place opposite to the Herr Professor, lounged Lieutenant Edward Mildmay, R.N. The lieutenant was skimming through the daily papers. Presently he looked up and remarked to the colonel: "I see that some Frenchmen have been making experiments in the navigation of balloons." "Ah, indeed!" responded the colonel, with his head thrown critically on one side, and his eyes still fixed on the reflection of the picture. "And with what result?" "Oh, failure, of course." "And failure it always will be. The thing is simply an impossibility," remarked the colonel. "No, bardon me, colonel, id is not an imbossibilidy by any means." This from the professor. "Indeed? Then how do you account for it, professor, that all attempts to navigate a balloon have hitherto failed?" asked the colonel. "Begause, my dear zir, the aeronauts have never yed realised all the requiremends of zuccess," replied the professor, laying down his magazine as though quite prepared to go thoroughly into the question. The colonel accepted the challenge, and, rousing himself from his semi- recumbent posture, said: "That is quite possible; but what _are_ the requirements of success?" The professor knocked the ashes out of his meerschaum, refilled it with the utmost deliberation, carefully lighted it, gave a few vigorous puffs, and replied: "The requiremends of zuccess in balloon navigation are very zimilar to those which enable a man to draverse the ocean. If a man wants to make a voyage agross the ocean he embargs in a ship, not on a life-buoy. Now a balloon is nothing more than a life-buoy; id zusdains a man, but that is all. Id drifts aboud with the currends of air jusd as a life-buoy drifts aboud with the currends of ocean, and the only advandage which the aeronaud has over the man with the life-buoy is thad the former can ascend or descend in search of a favourable air currend, whereas the ladder is obliged do dake the ocean currends as they come." "Very true," remarked the colonel; "and what do you deduce from that, professor?" "I deduse from thad thad the man who wands to navigade the air musd do as his brother the sailor does, he musd have a _ship_." "Well, is not a balloon a sort of air ship?"