"I'm sure we will," answered the aeronaut. "Now let's make another
model container, and try the gas again."

They set to work, with Mr. Swift helping them occasionally, and Garret
Jackson, the engineer, lending a hand whenever he was needed. All that
afternoon work on the airship progressed. The joint inventors of it
wanted to be sure that the sustaining gas bag, or aluminum container,
would do its work properly, as this would hold them in the air, and
prevent accidents, in case of a stoppage of the engine or propellers.

The aeroplane part of the airship was all but finished, and the motor,
a powerful machine, of new design, built by Mr. Swift, was ready to be
installed.

All that afternoon Tom, his father and Mr. Sharp labored in the shop.
As it grew dusk there sounded from the house the ringing of a bell.

"Supper time," remarked Tom, laying aside a wrench. "I wish Mrs.
Baggert would wait about an hour. I'd have this valve nearly done,
then."

But the housekeeper was evidently not going to wait, for her voice
supplemented the bell.

"Supper! Sup-per!" she called. "Come now, Mr. Swift; Tom, Mr. Sharp! I
can't wait any longer! The meat and potatoes will be spoiled!"

"I s'pose we'd better go in," remarked Mr. Sharp, with something of a
sigh. "We can finish to-morrow."