"Hurrah! hurrah!" shouted the brave fellow exultingly, as the Victoria, once more relieved, shot up again to a height of three hundred feet.

The Talabas spurred their horses, which now came tearing on at a furious gallop; but the balloon, falling in with a much more favorable wind, shot ahead of them, and was rapidly carried toward a hill that stretched across the horizon to the westward. This was a circumstance favorable to the aeronauts, because they could rise over the hill, while Al-Hadji's horde had to diverge to the northward in order to pass this obstacle.

The three friends still clung to the network. They had been able to fasten it under their feet, where it had formed a sort of swinging pocket.

Suddenly, after they had crossed the hill, the doctor exclaimed: "The river! the river! the Senegal, my friends!"

And about two miles ahead of them, there was indeed the river rolling along its broad mass of water, while the farther bank, which was low and fertile, offered a sure refuge, and a place favorable for a descent.

"Another quarter of an hour," said Ferguson, "and we are saved!"

But it was not to happen thus; the empty balloon descended slowly upon a tract almost entirely bare of vegetation. It was made up of long slopes and stony plains, a few bushes and some coarse grass, scorched by the sun.

The Victoria touched the ground several times, and rose again, but her rebound was diminishing in height and length. At the last one, it caught by the upper part of the network in the lofty branches of a baobab, the only tree that stood there, solitary and alone, in the midst of the waste.

"It's all over," said Kennedy.

"And at a hundred paces only from the river!" groaned Joe.

The three hapless aeronauts descended to the ground, and the doctor drew his companions toward the Senegal.

At this point the river sent forth a prolonged roaring; and when Ferguson reached its bank, he recognized the falls of Gouina. But not a boat, not a living creature was to be seen. With a breadth of two thousand feet, the Senegal precipitates itself for a height of one hundred and fifty, with a thundering reverberation. It ran, where they saw it, from east to west, and the line of rocks that barred its course extended from north to south. In the midst of the falls, rocks of strange forms started up like huge ante-diluvian animals, petrified there amid the waters.

The impossibility of crossing this gulf was self-evident, and Kennedy could not restrain a gesture of despair.

But Dr. Ferguson, with an energetic accent of undaunted daring, exclaimed--

"All is not over!"

"I knew it," said Joe, with that confidence in his master which nothing could ever shake.

The sight of the dried-up grass had inspired the doctor with a bold idea. It was the last chance of escape. He led his friends quickly back to where they had left the covering of the balloon.

"We have at least an hour's start of those banditti," said he; "let us lose no time, my friends; gather a quantity of this dried grass; I want a hundred pounds of it, at least."

"For what purpose?" asked Kennedy, surprised.

"I have no more gas; well, I'll cross the river with hot air!"

"Ah, doctor," exclaimed Kennedy, "you are, indeed, a great man!"

Joe and Kennedy at once went to work, and soon had an immense pile of dried grass heaped up near the baobab.

In the mean time, the doctor had enlarged the orifice of the balloon by cutting it open at the lower end. He then was very careful to expel the last remnant of hydrogen through the valve, after which he heaped up a quantity of grass under the balloon, and set fire to it.

It takes but a little while to inflate a balloon with hot air. A head of one hundred and eighty degrees is sufficient to diminish the weight of the air it contains to the extent of one-half, by rarefying it. Thus, the Victoria quickly began to assume a more rounded form. There was no lack of grass; the fire was kept in full blast by the doctor's assiduous efforts, and the balloon grew fuller every instant.