with here and there big open
places. If you are skimming along close to the ground, in an open
place, in pursuit of a herd of elephants and they should suddenly
plunge into the forest, you would want to be able to rise above the
trees quickly."

"That's so," admitted Tom. "Then I'll have to use a smaller gas bag
than we had on the other ship, for the air resistance to that big
one made us go slowly at times."

"Will it be as safe with a small bag?" Mr. Damon wanted to know.

"Yes, for I will use a more powerful gas, so that we will be more
quickly lifted," said the young inventor. "I will also retain the
aeroplane feature, so that the Black Hawk will be a combined biplane
and dirigible balloon. But it will have many new features. I have
the plans all drawn for a new style of gas generating apparatus, and
I think it can be made in time."

There were busy days about the Swift home. Mrs. Baggert, the
housekeeper, was in despair. She said the good meals she got ready
were wasted, because no one would come to table when they were
ready. She would ring the bell, and announce that dinner would be
served in five minutes.

Then Tom would shout from his workshop that he could not leave until
he had inserted a certain lever in place. Mr. Jackson would
positively decline to sit down until he had screwed fast some part
of a machine. Even Mr. Swift, who, because of his recent illness,
was not allowed to do much, would often delay his meal to test some
new style of gears.

As for Mr. Damon, it was to be expected that he would be eccentric
as he always was. He was not an expert mechanic, but he knew
something of machinery and was of considerable help to Tom in the
rush work on the airship. He would hear the dinner bell ring, and
would exclaim:

"Bless my napkin ring! I can't come now. I have to fix up this
electrical register first."

And so it would go. Eradicate and Boomerang, his mule, were the only
ones who ate regularly, and they always insisted on stopping at
exactly twelve o'clock to partake of the noonday meal.

"'Cause ef I didn't," explained the colored man, "dat contrary mule
ob mine would lay down in de dust ob de road an' not move a step,
lessen' he got his oats. So dat's why we has t' eat, him an' me."

"Well, I'm glad there's some one who's got sense," murmured Mrs.
Baggert. Eradicate and Boomerang were of great service in the
hurried work that followed, for the colored man in his cart brought
from town,