“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.
It was then a quarter to four o’clock.
At this moment the band of Talabas reappeared about two miles to the northward, and the three friends could hear their cries, and the clatter of their horses galloping at full speed.
“In twenty minutes they will be here!” said Kennedy.
“More grass! more grass, Joe! In ten minutes we shall have her full of hot air.”
“Here it is, doctor!”