A little farther on, Kennedy called out: "Look at that strange tree! The upper part is of one kind and the lower part of another!"

"Well!" said Joe, "here's a country where the trees grow on top of each other."

"It's simply the trunk of a fig-tree," replied the doctor, "on which there is a little vegetating earth. Some fine day, the wind left the seed of a palm on it, and the seed has taken root and grown as though it were on the plain ground."

"A fine new style of gardening," said Joe, "and I'll import the idea to England. It would be just the thing in the London parks; without counting that it would be another way to increase the number of fruit-trees. We could have gardens up in the air; and the small house-owners would like that!"

At this moment, they had to raise the balloon so as to pass over a forest of trees that were more than three hundred feet in height--a kind of ancient banyan.

"What magnificent trees!" exclaimed Kennedy. "I never saw any thing so fine as the appearance of these venerable forests. Look, doctor!"

"The height of these banyans is really remarkable, my dear Dick; and yet, they would be nothing astonishing in the New World."

"Why, are there still loftier trees in existence?"

"Undoubtedly; among the 'mammoth trees' of California, there is a cedar four hundred and eighty feet in height. It would overtop the Houses of Parliament, and even the Great Pyramid of Egypt. The trunk at the surface of the ground was one hundred and twenty feet in circumference, and the concentric layers of the wood disclosed an age of more than four thousand years."

"But then, sir, there was nothing wonderful in it! When one has lived four thousand years, one ought to be pretty tall!" was Joe's remark.

Meanwhile, during the doctor's recital and Joe's response, the forest had given place to a large collection of huts surrounding an open space. In the middle of this grew a solitary tree, and Joe exclaimed, as he caught sight of it:

"Well! if that tree has produced such flowers as those, for the last four thousand years, I have to offer it my compliments, anyhow," and he pointed to a gigantic sycamore, whose whole trunk was covered with human bones. The flowers of which Joe spoke were heads freshly severed from the bodies, and suspended by daggers thrust into the bark of the tree.

"The war-tree of these cannibals!" said the doctor; "the Indians merely carry off the scalp, but these negroes take the whole head."

"A mere matter of fashion!" said Joe. But, already, the village and the bleeding heads were disappearing on the horizon. Another place offered a still more revolting spectacle--half-devoured corpses; skeletons mouldering to dust; human limbs scattered here and there, and left to feed the jackals and hyenas.

"No doubt, these are the bodies of criminals; according to the custom in Abyssinia, these people have left them a prey to the wild beasts, who kill them with their terrible teeth and claws, and then devour them at their leisure.

"Not a whit more cruel than hanging!" said the Scot; "filthier, that's all!"

"In the southern regions of Africa, they content themselves," resumed the doctor, "with shutting up the criminal in his own hut with his cattle, and sometimes with his family. They then set fire to the hut, and the whole party are burned together. I call that cruel; but, like friend Kennedy, I think that the gallows is quite as cruel, quite as barbarous."

Joe, by the aid of his keen sight, which he did not fail to use continually, noticed some flocks of birds of prey flitting about the horizon.

"They are eagles!" exclaimed Kennedy, after reconnoitring them through the glass, "magnificent birds, whose flight is as rapid as ours."

"Heaven preserve us from their attacks!" said the doctor, "they are more to be feared by us than wild beasts or savage tribes."

"Bah!" said the hunter, "we can drive them off with a few rifle-shots."

"Nevertheless, I would prefer, dear Dick, not having to rely upon your skill, this time, for the silk of our balloon could not resist their sharp beaks; fortunately, the huge birds will, I believe, be more frightened than attracted by our machine."

"Yes! but a new idea, and I have dozens of them," said Joe; "if we could only manage to capture a team of live eagles, we could hitch them to the balloon, and they'd haul us through the air!"

"The thing has been seriously proposed," replied the doctor, "but I think it hardly practicable with creatures naturally so restive."

"Oh! we'd tame them," said Joe.