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
