For a moment after Tom's departure the others stared blankly at one another. They could hear the throbbing and hum of the machinery, and feel the thrill of the anchored airship. But they could not understand what the trouble was.

"We must help Tom!" cried Ned Newton at length as he caught up his rifle. "Maybe we are in the midst of a herd of elephants, and they have hold of the ship in their trunks."

"It couldn't be!" declared Mr. Durban, yet they soon discovered that Ned's guess was nearer the truth then any of them had suspected at the time.

"We must help him, true enough!" declared Mr. Anderson, and he and the others followed Ned out on deck.

"Where are you Tom?" called his chum.

"Here." was the answer. "I'm on the forward deck."

"Do you see anything?"

"No, it's too dark. Turn the search-light this way."

"I will," shouted Mr. Damon, and a moment later the gleam of the powerful lantern brought Tom clearly into view, as he stood on the small forward observation platform in the bow of the Black Hawk.

An instant later the young inventor let out a startled cry.

"What is it?" demanded Mr. Durban.

"An immense snake!" shouted Tom. "It's wound around a tree, and partly twined around the ship! That's why we couldn't go up! I'm going to shoot it."

They looked to where he pointed, and there, in the glare of the light, could be seen an immense python, fully twenty-five feet long, the forward part of its fat ugly body circled around the slender prow of the airship, while the folds of the tail were about a big tree.

Tom Swift raised his electric rifle, took quick aim, and, having set it to deliver a moderate charge, pressed the button. The result was surprising, for the snake being instantly killed the folds uncoiled and the ship shot upward, only, instead of rising on an even keel, the bow pointed toward the sky, while the stern was still fast to the earth. Tilted at an angle of forty-five degrees the Black Hawk was in a most peculiar position, and those standing on the deck began to slide along it.

"There's another snake at the stern!" cried Mr. Damon as he grasped a brace to prevent falling off. "Bless my slippers! it's the mate of the one you killed! Shoot the other one, Tom!"

The young inventor needed no urging. Making his way as best he could to the stern of the airship, he killed the second python, which was even larger than the first, and in an instant the Black Hawk shot upward, this time level, and as it should be. Things on board were soon righted, and the travelers could stand upright. High above the black jungle rose the craft, moving forward under the full power of the propellers, until Tom rushed into the engine room, and reduced speed.

"Well, talk about things happening!" exclaimed Ned, when they had somewhat recovered from the excitement. "I should say they were beginning with a vengeance!"

"That's the way in Africa," declared Mr. Durban. "It's a curious country. Those pythons generally go in pairs, but it's the first time I ever knew them to tackle an airship. They probably stay around here where there is plenty of small game for them, and very likely they merely anchored to our craft while waiting for a supper to come along."

"It was a very odd thing," said Tom. "I couldn't imagine what held us. After this I'll see that all is clear before I try to go up. Next time we may he held by a troop of baboons and it strains the machinery to have it pull against dead weight in that way."

However, it was found no harm had resulted from this experience, and, after reducing the gas pressure, which was taking them too high, Tom set the automatic rudders.

"We'll keep on at slow speed through the night," he explained, "and in the morning we'll be pretty well into the interior. Then we can lay our course for wherever we want to go. Where had we better head for?"

"I don't want to interfere with your plans," said Mr. Anderson, "but I would like to rescue those missionaries. But the trouble is, I don't know just where to look for them. We couldn't get much of a line in Majumba on where the country of the red pygmies is located. What do you think about it, Mr. Durban?"

"As far as elephant hunting goes we can probably do as well in the pygmy land as anywhere else," answered the veteran, "and perhaps it will be well to head for that place. If we run across any elephant herds in the meanwhile, we can stop, get the ivory, and proceed."

They discussed this plan at some length, and agreed that it was the best thing to do. Mr. Durban had a map of the country around the center of Africa, and he marked on it, as nearly as he could, the location of the pygmies' country, while Mr. Anderson also had a chart, showing the location of the mission which had been wiped out of existence. It was in the midst of a wild and desolate region.

"We'll do the best we can," declared Tom, "and I think we'll succeed. We ought to be there in about a week, if we have no bad luck."

All that night the Black Hawk flew on over Africa, covering mile after mile, passing over jungle, forest, plains, rivers and lakes, and, doubtless, over many native villages, though they could not be seen.

Morning found the travelers above a great, grassy plain, dotted here and there with negro settlements which were separated by rivers, lakes or thin patches of forest.

"Well, we'll speed up a bit," decided Tom after breakfast, which was eaten to the weird accompaniment of hundreds of native warning- drums, beaten by the superstitious blacks.

Tom went to the engine room, and turned on more speed. He was about to go back to the pilot house, to set the automatic steering apparatus to coincide with the course mapped out, when there was a crash of metal, an ominous snapping and buzzing sound, followed by a sudden silence.

"What's that?" cried Ned, who was in the motor compartment with his chum.

"Something's gone wrong!" exclaimed the young inventor, as he sprang back toward the engine. The propellers had ceased revolving, and as there was no gas in the bag at that time, it having been decided to save the vapor for future needs, the Black Hawk began falling toward the earth.

"We're going down!" yelled Ned.

"Yes, the main motor has broken!" exclaimed Tom. "We'll have to descend to repair it."

"Say!" yelled Mr. Damon, rushing in, "we're right over a big African village! Are we going to fall among the natives?"

"It looks that way," admitted Tom grimly, as he hastened to the pilot house to shift the wings so that the craft could glide easily to the ground.

"Bless my shoe blacking!" cried the eccentric man as he heard the beating of drums, and the shouts of the savages.

A little later the airship had settled into the midst of a crowd of Africans, who swarmed all about the craft.