aced in the
various rooms of the airship's cabin, until the balloon shed was
stripped quite bare. The professor was busy in the engine room. The
noise of the gas generating machine increased.

Then came a series of sharp explosions as one of the gasolene engines
was started. This was followed by the hum of an electric dynamo, and the
whizz and purring of a big motor.

The inventor was testing the many machines to see that all worked right.
Suddenly he switched on the incandescent lights in the ship's cabin.
Next he turned on the powerful searchlight in the bow, and the shed was
illuminated by a glare that rivaled the sun. The professor then revolved
the big propeller slowly and tested the rudder.

"Everything is in good shape!" he cried. "We will start in five minutes
if they get the roof off so we can rise. Those anchor ropes will not
hold much longer!"

Up on the roof, however, the men were working with a will. Board after
board was torn away and the different sections moved to one side. At
last the whole top of the shed was off. All that remained was to let the
_Monarch_ out.

Suddenly from where the three emergency helpers were working there came
a cry of astonishment, mingled with fear. For the first time Andy Sudds,
Tom Smith and Bill Jones, characters well known to Amos Henderson, had
looked down into the shed, and caught sight of the tugging, swaying
airship. The interior had been quite dark up to this point, which
accounted for them not having noticed the ship before. But when they saw
the strange affair so close beneath them they were startled.

"Jumpin' rattlesnakes!" cried Andy Sudds. "What have I struck?"

"It's a yellow elephant!" exclaimed Tom Jones.

"A sea serpent!" ejaculated Bill Smith.

They leaned over from the edge of the roof eaves to which they were
clinging and peered down into the big balloon shed. Certainly the
airship presented a queer sight to the three men.

"Is everything ready?" asked the professor of Washington.

"Eberyt'ing am circumulated to completeness," replied the negro.

"Jump in, boys! Untie the ropes, Washington. We'll start!"

"Hurry! Hurry! Perfessor!" cried Washington, as he looked out of a side
window. "Here comes dat man we tied up in de shed! He's got anoder man
wid him, an' dey got guns!"

"It's Taggert! He is after me!" exclaimed the inventor. "He must not
be allowed to get on the ship! Come on, Mark and Jack! Never mine
unknotting the ropes! Cut 'em! We