There are few animals in Africa more dreaded by hunters than the wild buffalo, for the beast, with its spreading sharp horns is a formidable foe, and will seldom give up the attack until utterly unable to move. They are fierce and relentless. "Look out!" yelled Mr. Durban. "To cover, everybody! If that beast gets after you it's no fun! You and I will fire at him, Mr. Anderson!" Mr. Durban raised his rifle, and pulled the trigger, but, for some reason, the weapon failed to go off. Mr. Anderson quickly raised his, but his foot slipped in a wet place and he fell. At that moment the buffalo, with a snort of rage, charged straight for the fallen man. "Tom! your electric rifle!" yelled Ned Newton, but he need not have done so, for the young inventor was on the alert. Taking instant aim, and adjusting his weapon for the heaviest charge, Tom fired at the advancing beast. The result was the same as in the case of the whale, the buffalo seemed to melt away. And it was stopped only just in time, too, for it was close to the prostrate Mr. Anderson, who had sprained his ankle slightly, and could not readily rise. It was all over in a few seconds, but it was a tense time while it lasted. "You saved my life again, Tom Swift," said Mr. Anderson, as he limped toward our hero. "Once on Earthquake Island, and again now. I shan't forget it," and he shook hands with the young inventor. The others congratulated Tom on his quick shot, and Mr. Damon, as usual blessed everything in sight, and the electric rifle especially. They went back to the airship, taking the fresh meat with them, but on account of the injury to Mr. Anderson's ankle could not make quick progress, so that it was almost dusk when they reached the craft. "Well, we'll have supper, and then start off," proposed Tom, "I don't think it would be wise to remain on the ground so near the jungle." "No' it's safer in the air," agreed Mr. Durban. The meal was much enjoyed, especially the fresh meat, and, after it was over, Tom took his place in the pilot house to start the machinery, and send the airship aloft. The motor hummed and throbbed, and the gas hissed into the bag, for the ground was not level enough to permit of a running start by means of the planes. Lights gleamed from the Black Hawk and the big search-lantern in front cast a dazzling finger of light into the black forest. "Well, what are you waiting for?" called Ned, who heard the machinery in motion, but who could not feel the craft rising. "Why don't you go up, Tom?" "I'm trying to," answered the young inventor. "Something seems to be the matter." He pulled the speed lever over a few more notches, and increased the power of the gas machine. Still the Black Hawk did not rise. "Bless my handkerchief box!" cried Mr. Damon, "what's the matter?" "I don't know," answered Tom. "We seem to be held fast."