"HERE! Stop him!" cried Professor Henderson. "Don't let him get away.
We still need his help to get the ship in shape. He needn't be
frightened. We're not going to start at once."

Mark and Jack ran after Washington, whose progress was somewhat
impeded because he kept looking back as if he feared the new ship was
chasing him.

"Come on back!" said Mark. "There's no danger, and if there was we're
not going to start to-day."

"Ain't yo' foolin' me?" asked Washington, pausing and looking
doubtfully at the boys.

"Of course not," answered Mark. "You know Professor Henderson would
not make you do anything you didn't want to do, Wash. He wishes you to
stay and help him get ready, that's all."

"Well, Washington," observed the aged scientist. "I didn't think you'd
go back on me."

"I'd do mos' anything fer yo', Perfesser," said the colored man, "but
I got t' beg off this time," and he looked at the Flying Mermaid as if
he thought the metal sides would open and devour him.

Then help me get things in shape to generate the gas," the scientist
said. "I want to give the new vapor the first real test in lifting
power to-day. On the success of it depends the future of the ship."