Tom Swift's former airship, the Red Cloud, had been such a fine craft, and had done such good service that he thought, in building a successor, that he could do no better than to follow the design of the skyship which had been destroyed in the ice caves. But, on talking with the old elephant hunter, and learning something of the peculiarities of the African jungle the young inventor decided on certain changes.

In general the Black Hawk would be on the lines of the Red Cloud but it would be smaller and lighter and would also be capable of swifter motion.

"You want it so that it will rise and descend quickly and at sharp angles," said Mr. Durban.

"Why," inquired Tom.

"Because in Africa, at least in the part where we will go, there are wide patches of jungle and forest, 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, or from the freight depot, many things that Tom needed.

The young inventor was very enthusiastic about his proposed trip, and at night, after a hard day's work in the shop, he would read books on African hunting, or he would sit and listen to the stories told by Mr. Durban. And the latter knew how to tell hunting tales, for he had been long in his dangerous calling, and had had many narrow escapes.

"And there are other dangers than from elephants and wild beasts in Africa," he said.

"Bless my toothbrush!" exclaimed Mr. Damon. "Do you mean cannibals, Mr. Durban?"

"Some cannibals," was the reply. "but they're not the worst. I mean the red pygmies. I hope we don't get into their clutches."

"Red pygmies!" repeated Tom, wonderingly.

"Yes, they're a tribe of little creatures, about three feet high, covered with thick reddish hair, who live in the central part of Africa, near some of the best elephant-hunting ground. They are wild, savage and ferocious, and what they lack individually in strength, they make up in numbers. They're like little red apes, and woe betide the unlucky hunter who falls into their merciless hands. They treat him worse than the cannibals do."

"Then we'll look out for them," said Tom. "But I fancy my electric rifle will make them give us a wide berth."

"It's a great gun," admitted the old hunter with a shake of his head, "but those red pygmies are terrible creatures. I hope we don't get them on our trail. But tell me, Tom, how are you coming on with the airship? for I don't know much about mechanics, and to me it looks as if it would never be put together. I's like one of those queer puzzles I've seen 'em selling in the streets of London."

"Oh, it's nearer ready than it looks to be," said Tom. "We'll have it assembled, and ready for a trial in about two weeks more."

Work on the Black Hawk was rushed more than ever in the next few days, another extra machinist being engaged. Then the craft began to assume shape and form, and with the gas bag partly inflated and the big planes stretching out from either side, it began to look something like the ill-fated Red Cloud.

"It's going to be a fine ship!" cried Tom enthusiastically, one day, as he went to the far side of the ship to get a perspective view of it. "We'll make good time in this."

"Are you going to sail all the way to Africa--across the ocean--in her?" asked Mr. Durban, in somewhat apprehensive tones.

"Oh, no," replied Tom. "I believe she would be capable of taking us across the ocean, but there is no need of running any unnecessary risks. I want to get her safely to Africa, and have her do stunts in elephant land."

"Then what are your plans?" asked the hunter.

"We'll put her together here," said Tom, "give her a good try-out to see that she works well, and then pack her up for shipment to the African coast by steamer. We'll go on the same ship, and when we arrive we'll put the Black Hawk together again, and set sail for the interior."

"Good idea," commented Mr. Durban. "Now, if you've no objections, I'm going to do a little practice with the electric rifle."

"Go ahead," assented Tom. "There comes Ned Newton; he'll be glad of a chance for a few shots while I work on this new propeller motor. It just doesn't suit me."

The bank clerk, who had arranged to go to Africa with Tom, was seen advancing toward the aeroplane shed. In his hand Ned held a paper, and as he saw Tom he called out:

"Have you heard the news?"

"What news?" inquired the young inventor.

"About Andy Foger. He and his aeroplane are lost!"

"Lost!" cried Tom, for in spite of the mean way the bully had treated him our hero did not wish him any harm.

"Well, not exactly lost," went on Ned, as he held out the paper to Tom, "but he and his sky-craft have disappeared."

"Disappeared?"

"Yes. You know he and that German, Mr. Landbacher, went over to Europe to give some aviation exhibitions. Well, I see by this paper that they went to Egypt, and were doing a high-flying stunt there, when a gale sprang up, they lost control of the aeroplane and it was swept out of sight."

"In which direction; out to sea?"

"No, toward the interior of Africa."

"Toward the interior of Africa!" cried Tom. "And that's where we're going in a couple of weeks. Andy in Africa!"

"'Maybe we'll see him there," suggested Ned.

"Well, I certainly hope we do not!" exclaimed Tom, as he turned back to his work, with an undefinable sense of fear in his heart.