In that memorable day, the 23d of April, they had, in fifteen hours, impelled by a rapid breeze, traversed a distance of more than three hundred and fifteen miles.

But this latter part of the journey had left them in dull spirits, and complete silence reigned in the car. Was Dr. Ferguson absorbed in the thought of his discoveries? Were his two companions thinking of their trip through those unknown regions? There were, no doubt, mingled with these reflections, the keenest reminiscences of home and distant friends. Joe alone continued to manifest the same careless philosophy, finding it QUITE NATURAL that home should not be there, from the moment that he left it; but he respected the silent mood of his friends, the doctor and Kennedy.

About ten the balloon anchored on the side of the Trembling Mountain, so called, because, in Arab tradition, it is said to tremble the instant that a Mussulman sets foot upon it. The travellers then partook of a substantial meal, and all quietly passed the night as usual, keeping the regular watches.

On awaking the next morning, they all had pleasanter feelings. The weather was fine, and the wind was blowing from the right quarter; so that a good breakfast, seasoned with Joe's merry pranks, put them in high good-humor.

The region they were now crossing is very extensive. It borders on the Mountains of the Moon on one side, and those of Darfur on the other--a space about as broad as Europe.

"We are, no doubt, crossing what is supposed to be the kingdom of Usoga. Geographers have pretended that there existed, in the centre of Africa, a vast depression, an immense central lake. We shall see whether there is any truth in that idea," said the doctor.

"But how did they come to think so?" asked Kennedy.

"From the recitals of the Arabs. Those fellows are great narrators--too much so, probably. Some travellers, who had got as far as Kazeh, or the great lakes, saw slaves that had been brought from this region; interrogated them concerning it, and, from their different narratives, made up a jumble of notions, and deduced systems from them. Down at the bottom of it all there is some appearance of truth; and you see that they were right about the sources of the Nile."

"Nothing could be more correct," said Kennedy. "It was by the aid of these documents that some attempts at maps were made, and so I am going to try to follow our route by one of them, rectifying it when need be."

"Is all this region inhabited?" asked Joe.

"Undoubtedly; and disagreeably inhabited, too."

"I thought so."

"These scattered tribes come, one and all, under the title of Nyam-Nyams, and this compound word is only a sort of nickname. It imitates the sound of chewing."

"That's it! Excellent!" said Joe, champing his teeth as though he were eating; "Nyam-Nyam."

"My good Joe, if you were the immediate object of this chewing, you wouldn't find it so excellent."

"Why, what's the reason, sir?"

"These tribes are considered man-eaters."

"Is that really the case?"

"Not a doubt of it! It has also been asserted that these natives had tails, like mere quadrupeds; but it was soon discovered that these appendages belonged to the skins of animals that they wore for clothing."

"More's the pity! a tail's a nice thing to chase away mosquitoes."

"That may be, Joe; but we must consign the story to the domain of fable, like the dogs' heads which the traveller, Brun-Rollet, attributed to other tribes."

"Dogs' heads, eh? Quite convenient for barking, and even for man-eating!"

"But one thing that has been, unfortunately, proven true, is, the ferocity of these tribes, who are really very fond of human flesh, and devour it with avidity."

"I only hope that they won't take such a particular fancy to mine!" said Joe, with comic solemnity.

"See that!" said Kennedy.

"Yes, indeed, sir; if I have to be eaten, in a moment of famine, I want it to be for your benefit and my master's; but the idea of feeding those black fellows--gracious! I'd die of shame!"

"Well, then, Joe," said Kennedy, "that's understood; we count upon you in case of need!"

"At your service, gentlemen!"

"Joe talks in this way so as to make us take good care of him, and fatten him up."

"Maybe so!" said Joe.