“Eel-skins,” said Caspar, repeating the phrase, as he saw that Karl hesitated before pronouncing an opinion. “Don’t you think they would do?”

Karl had it on the tip of his tongue to cry out—“The very thing!” but something withheld him from making this unqualified declaration.

“They might—it is possible they might,” said he, apparently debating the question within himself—“just possible; and yet I fear—”

“What do you fear?” asked Caspar.

“Do you think they would not be strong enough?”

“Strong enough,” replied Karl. “That’s not what I fear.”

“The air can’t pass through an eel-skin?”

“No—not that.”

“At the seams, perhaps? We can stitch them neatly; and then gum them over at the joinings. I’ll warrant Ossaroo can sew like a shoemaker.”

The shikaree could do all that. Karl knew it. It was not there the difficulty lay.

“The weight, then?” pursued Caspar interrogatively.

“Precisely that,” answered Karl; “I fear they will be too heavy. Bring one, Ossaroo; and let us have a look at it.”

The shikaree rose from his seat; and going into the hovel, returned presently—bringing back with him a long shrivelled object, which any one could tell to be a dried eel-skin.

There were many like it inside: for they had carefully preserved the skins of the eels they had caught, induced to do so by a sort of presentiment, that some day they might find a use for them. In this case their prudent providence was likely to prove of service to them.

Karl took the skin; and, holding it out on the palm of his hand, appeared to make an estimate of its weight. Caspar watched his brother’s countenance, and waited to hear what he would say; but Karl only expressed himself by a doubtful shake of the head, which seemed to show that his opinion was against the eel-skins.

“They might be made much lighter, I fancy,” suggested Caspar: “scraping would do a deal for them; and by the way, why would not boiling make them light enough? It would take all the fatty, oily substance out of them.”

“There’s something in what you say,” rejoined Karl, apparently impressed by the last suggestion. “Boiling might render them a good deal lighter. We can easily try it.”

As Karl said this, he proceeded to the boiling spring, and plunged the eel-skin under the water. There it was permitted to remain for about half an hour, when it was taken out; and, after being scraped with the blade of a knife, was spread upon a rock, under the sun, where it would soon get thoroughly dry.

They all waited patiently for the completion of this process. The result was of too interesting a character to allow of their occupying themselves with anything else.

In due time the eel-skin had become sufficiently dry, to be submitted to examination; and Karl, once more taking it up, balanced it upon his palm.

Tested, even in this inexact fashion, it was evidently much lighter than before; and, by the gratified look with which the philosopher regarded it, he appeared to be much better satisfied with its weight. Still, however, he was not sanguine: as his words testified. They were almost a repetition of what he had said before.

“It may do—it is just possible. At all events, there can be no harm in trying. Let us try it, then.”

To say, “Let us try it,” meant the same as to say, “Let us make the balloon.” The others understood that; and of course acquiesced in the determination.

As there was nothing to interfere with the immediate commencement of the work, they resolved to set about it at once; and in fact did set about it without farther delay.

The number of eel-skins on hand, though very considerable, would not be near enough for covering a balloon; and therefore Ossaroo ............