“Why, just set fire to the batten,—that will be fastened under the mouth of the balloon by a bit of wire, you know,—and that’ll soon make the gas. Then away it goes, like a rocket.”

“I should think it might set something on fire,” said Will.

“Well, let it set. There are fire-engines enough in the town to put it out,” Henry replied, with easy indifference. “But, Will,” he added, “don’t be afraid; I’ve rigged lots of them, and they never set anything on fire yet.”

Ah, Henry! You did not observe that your balloons were generally fabricated so fragilely that it was impossible for them to do any harm!

“Then let us make one!” Will rejoined with alacrity.

The cousins, without delay, repaired to Mrs. Mortimer’s apartments, to look for some of the things required. Henry rummaged in a careless way that quite shocked poor Will, and at last issued from the room, leaving everything in appalling disorder. Next, Mr. Mortimer’s valuables were overhauled, and last of all, the hero’s own.

“Now we’ve found everything we need, Will, even to the tools,” he said. “Let us go to work.”

“Won’t you straighten up things, Henry?” Will ventured to ask.

“Straighten! Creation, no! Don’t you know it’s fall house-cleaning time? I don’t fool away my time in straightening!” with virtuous indignation.

Choosing Henry’s room for a workshop, the two fell to work. Notwithstanding the fact that the science of aëronautics was entirely new to him, Will suggested so many improvements that Henry was both astonished and delighted.