Higher and higher went the Black Hawk, far above the earth, until the old elephant hunter, looking down, said in a voice which he tried to make calm and collected, but which trembled in spite of himself: "Of course I'm not an expert at this game, Tom Swift, but it looks to me as if we'd never get down. Don't you think we're high enough?" "For the time being, yes," answered the young inventor. "I didn't think she'd climb so far without the use of the gas. She's doing well." "Bless my topknot, yes!" exclaimed Mr. Damon. "She beats the Red Cloud, Tom. Try her on a straight-away course." Which the youth did, pointing the nose of the craft along parallel to the surface of the earth, and nearly a mile above it. Then, increasing the speed of the motor, and with the big propellers humming, they made fast time. The old elephant hunter grew more calm as he saw that the airship did not show any inclination to fall, and he noted that Tom and the others not only knew how to manage it, but took their flight as much a matter of course as if they were in an automobile skimming along on the surface of the ground. Tom put his craft through a number of evolutions, and when he found that she was in perfect control as an aeroplane, he started the gas machine, filled the big black bag overhead, and, when it was sufficiently buoyant, he shut off the motor, and the Black Hawk floated along like a balloon. "That's what we'll do if our power happens to give out when we get over an African jungle, with a whole lot of wild elephants down below, and a forest full of the red pygmies waiting for us," explained Tom to Mr. Durban. "And I guess you'll need to do it, too," answered the hunter. "I don't know which I fear worse, the bad elephants wild with rage, as they get some times, or the little red men who are as strong as gorillas, and as savage as wolves. It would be all up with us if we got into their hands. But I think this airship will be just what we need in Africa. I'd have been able to get out of many a tight place if I had had one on my last trip." While the Black Hawk hung thus, up the air, not moving, save as the wind blew her, Tom with his father and Mr. Jackson made an inspection of the machinery to find out whether it had been strained any. They found that it had worked perfectly, and soon the craft was in motion again, her nose this time being pointed toward the earth. Tom let out some of the gas, and soon the airship was on the ground in front of the shed she had so recently left. "She's all right," decided the young inventor after a careful inspection. "I'll give her a couple more trials, put on the finishing touches and then we'll be ready for our trip to Africa. Have you got everything arranged to go, Ned?" "Sure. I have a leave of absence from the bank, thanks to your father and Mr. Damon, most of my clothes are packed, I've bought a gun and I've got a lot of quinine in case I get a fever."