"I've seen one something like that," spoke Innis.

"Where?" his chums wanted to know, as Dick slowed down his boat,
the better to watch the biplane, which was now circling over the
river.

"Why, a cousin of mine, Whitfield Vardon by name, has the airship
craze pretty bad," resumed Innis. "He has an idea he can make one
that will maintain its equilibrium no matter how the wind blows or
what happens. But, poor fellow, he's spent all his money on
experiments and he hasn't succeeded. The last I heard, he was about
down and out, poor chap. He showed me a model of his machine once,
and it looked a lot like this. But this one seems to work, and his
didn't--at least when I saw it."

"It's mighty interesting to watch, all right," spoke Paul, "but
we'll be in for a wigging if we miss guard-mount. Better speed her
along, Dick."

"Yes, I guess so. But we've got time--"

Dick never finished that sentence. Innis interrupted him with a
cry of:

"Look, something's wrong on that aircraft!"

"I should say so!" yelled Paul. "They've lost control of her!"

The big biplane was in serious difficulties, for it gave a lurch,
turned turtle, and then, suddenly righting, shot downward for the