"Two weeks' rest will make you well," declared Jack, as he adjusted
the controls.

"Good-by and good luck," said his father.

Both boys waved their hands.

"All ready, Tom?" hailed Jack.

The other boy nodded and then turned on a valve so that with a hissing
sound additional gas rushed into the bag. Jack pulled a lever. The big
motors roared and a queer, sickly smell of burned gas filled the air.
The propellers began to revolve slowly and then increased their speed
till they became a mere blur.

"Dere she go! Gollyumption, dere she go!" cried Jupe, capering about.

As the old black spoke, the Wondership shot up like a rocket, tilting
her nose slightly into the air. But the next moment Jack had her on an
even keel. In an incredibly short space of time those watching below
saw her only as a glinting, golden speck against the blue sky,
circling like some strange bird far above their heads.

"Now for the tests," said Mr. Chadwick, as he hastened to his
workshop.

He set the big alternator at work at top speed. It droned like a gaunt
bee. The inventor's face, worn by his anxious vigils at his
experiments, was as keen as a hawk's, while he adjusted the
instruments and placed his long, lean fingers on the tuning device.