The acquaintanceship of these two friends had been formed in India, when they belonged to the same regiment. While Dick would be out in pursuit of the tiger and the elephant, Samuel would be in search of plants and insects. Each could call himself expert in his own province, and more than one rare botanical specimen, that to science was as great a victory won as the conquest of a pair of ivory tusks, became the doctor’s booty. These two young men, moreover, never had occasion to save each other’s lives, or to render any reciprocal service. Hence, an unalterable friendship. Destiny sometimes bore them apart, but sympathy always united them again. Since their return to England they had been frequently separated by the doctor’s distant expeditions; but, on his return, the latter never failed to go, not to _ask_ for hospitality, but to bestow some weeks of his presence at the home of his crony Dick. The Scot talked of the past; the doctor busily prepared for the future. The one looked back, the other forward. Hence, a restless spirit personified in Ferguson; perfect calmness typified in Kennedy—such was the contrast. After his journey to the Thibet, the doctor had remained nearly two years without hinting at new explorations; and Dick, supposing that his friend’s instinct for travel and thirst for adventure had at length died out, was perfectly enchanted. They would have ended badly, some day or other, he thought to himself; no matter what experience one has with men, one does not travel always with impunity among cannibals and wild beasts. So, Kennedy besought the doctor to tie up his bark for life, having done enough for science, and too much for the gratitude of men. The doctor contented himself with making no reply to this. He remained absorbed in his own reflections, giving himself up to secret calculations, passing his nights among heaps of figures, and making experiments with the strangest-looking machinery, inexplicable to everybody but himself. It could readily be guessed, though, that some great thought was fermenting in his brain. “What can he have been planning?” wondered Kennedy, when, in the month of January, his friend quitted him to return to London. He found out one morning when he looked into the _Daily Telegraph_. “Merciful Heaven!” he exclaimed, “the lunatic! the madman! Cross Africa in a balloon! Nothing but that was wanted to cap the climax! That’s what he’s been bothering his wits about these two years past!” Now, reader, substitute for all these exclamation points, as many ringing thumps with a brawny fist upon the table, and you have some idea of the manual exercise that Dick went through while he thus spoke. When his confidential maid-of-all-work, the aged Elspeth, tried to insinuate that the whole thing might be a hoax—