"Out in my shop, running yet if it hasn't been frightened by the airship smash," replied the lad, somewhat proudly. "It's an oxide of nickel battery, with steel and oxide of iron negative electrodes."

"What solution do you use, Tom?" asked Mr. Swift. "I didn't get that far in questioning you before the crash came," he added.

"Well I have, in the experimental battery, a solution of potassium hydrate," replied the lad, "but I think I'm going to change it, and add some lithium hydrate to it. I think that will make it stronger."

"Bless my watch chain!" exclaimed Mr. Damon. "It's all Greek to me. Suppose you let us see it, Tom? I like to see wheels go 'round, but I'm not much of a hand for chemical terms."

"If you're sure you're not hurt by the airship smash, I will," declared the lad.

"Oh, we're not hurt a bit," insisted Mr. Sharp. "As I said we were moving slow, for I knew it was about time to land. Mr. Damon was steering—"

"Yes I thought I'd try my hand at it, as it seemed so easy," interrupted the eccentric man. "But never again—not for mine! I couldn't see the house, and, before I knew it we were right over the roof. Then the chimney seemed to stick itself up suddenly in front of us, and—well, you know the rest. I'm willing to pay for any damage I caused."

"Oh, not at all!" replied Tom. "It's easy enough to put on a new plane, or, for that matter, we can operate the Red Cloud without it. But come on, I'll show you my sample battery."

"Here, take umbrellas!" Mrs. Baggert called after them as they started toward the shop, for it was still raining.

"We don't mind getting wet," replied the young inventor. "It's in the interests of science."