essed. 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."

The shop, where certain parts of the airship were being made, was
doubly locked, and Jackson, the engineer, who was also a sort of
watchman, was bidden to keep good guard, for the fear of the gang of
unscrupulous men, who had escaped from jail during a great storm, was
still in the minds of Mr. Swift and his son.

"And give an occasional look in the shed, where the aeroplane is,"
advised Mr. Sharp. "It wouldn't take much to damage that, now."

"I'll pay particular attention to it," promised the engineer. "Don't
worry, Mr. Sharp."

After supper the three gathered around the table on which were spread
out sheets of paper, covered with intricate figures and calculations,
which Mr. Swift and the balloonist went over with care. Tom was
examining some blue prints, which gave a sectional view of the proposed
ship, and was making some measurements when the bell rang, and Mrs.
Baggert ushered in Ned Newton, the most particular chum of the young
inventor.

"Hello, Ned!" exclaimed Tom. "I was wondering what had become of you.
Haven't seen you in a dog's age."

"That's right," admitted Ned. "We've been working late nights at the
bank. Getting ready for the regular visit of the examiner, who usually
comes along about this time. Well, how are things going; and how is the
airship?" for, of course, Ned had heard of that.

"Oh, pretty good. Had another explosion to-day, I s'pose you heard."

"No, I hadn't."

"I thought everyone in