"Kennedy! Kennedy! throw out your fire-arms, or we are lost!" shouted the doctor.

"Wait, sir; wait one moment!" they heard Joe exclaim, and, looking around, they saw Joe disappear over the edge of the balloon.

"Joe! Joe!" cried Kennedy.

"Wretched man!" was the doctor's agonized expression.

The flat top of the mountain may have had about twenty feet in breadth at this point, and, on the other side, the slope presented a less declivity. The car just touched the level of this plane, which happened to be quite even, and it glided over a soil composed of sharp pebbles that grated as it passed.

"We're over it! we're over it! we're clear!" cried out an exulting voice that made Ferguson's heart leap to his throat.

The daring fellow was there, grasping the lower rim of the car, and running afoot over the top of the mountain, thus lightening the balloon of his whole weight. He had to hold on with all his strength, too, for it was likely to escape his grasp at any moment.

When he had reached the opposite declivity, and the abyss was before him, Joe, by a vigorous effort, hoisted himself from the ground, and, clambering up by the cordage, rejoined his friends.

"That was all!" he coolly ejaculated.

"My brave Joe! my friend!" said the doctor, with deep emotion.

"Oh! what I did," laughed the other, "was not for you; it was to save Mr. Kennedy's rifle. I owed him that good turn for the affair with the Arab! I like to pay my debts, and now we are even," added he, handing to the sportsman his favorite weapon. "I'd feel very badly to see you deprived of it."

Kennedy heartily shook the brave fellow's hand, without being able to utter a word.

The Victoria had nothing to do now but to descend. That was easy enough, so that she was soon at a height of only two hundred feet from the ground, and was then in equilibrium. The surface seemed very much broken as though by a convulsion of nature. It presented numerous inequalities, which would have been very difficult to avoid during the night with a balloon that could no longer be controlled. Evening was coming on rapidly, and, notwithstanding his repugnance, the doctor had to make up his mind to halt until morning.

"We'll now look for a favorable stopping-place," said he.

"Ah!" replied Kennedy, "you have made up your mind, then, at last?"

"Yes, I have for a long time been thinking over a plan which we'll try to put into execution; it is only six o'clock in the evening, and we shall have time enough. Throw out your anchors, Joe!"

Joe immediately obeyed, and the two anchors dangled below the balloon.

"I see large forests ahead of us," said the doctor; "we are going to sweep along their tops, and we shall grapple to some tree, for nothing would make me think of passing the night below, on the ground."

"But can we not descend?" asked Kennedy.

"To what purpose? I repeat that it would be dangerous for us to separate, and, besides, I claim your help for a difficult piece of work."

The Victoria, which was skimming along the tops of immense forests, soon came to a sharp halt. Her anchors had caught, and, the wind falling as dusk came on, she remained motionlessly suspended above a vast field of verdure, formed by the tops of a forest of sycamores.

CHAPTER FORTY-SECOND.

A Struggle of Generosity.--The Last Sacrifice.--The Dilating Apparatus. --Joe's Adroitness.--Midnight.--The Doctor's Watch.--Kennedy's Watch. --The Latter falls asleep at his Post.--The Fire.--The Howlings of the Natives.--Out of Range.

Doctor Ferguson's first care was to take his bearings by stellar observation, and he discovered that he was scarcely twenty-five miles from Senegal.

"All that we can manage to do, my friends," said he, after having pointed his map, "is to cross the river; but, as there is neither bridge nor boat, we must, at all hazards, cross it with the balloon, and, in order to do that, we must still lighten up."

"But I don't exactly see how we can do that?" replied Kennedy, anxious about his fire-arms, "unless one of us makes up his mind to sacrifice himself for the rest,--that is, to stay behind, and, in my turn, I claim that honor."

"You, indeed!" remonstrated Joe; "ain't I used to--"

"The question now is, not to throw ourselves out of the car, but simply to reach the coast of Africa on foot.