“Hark!  What’s that?” cried Tom, raising his hand for silence.

“Bless my umbrella! it sounds like thunder,” said Mr. Damon.

“No, it’s one of their war drums,” explained Mr. Durban.  “The natives make large ones out of hollow trees, with animal skins stretched over the ends, and they beat them to sound a warning, or before going into battle.  It makes a great noise.”

“Do you think they want to fight us?” asked Ned, looking anxiously at Tom, and then toward where his rifle stood in a corner of the cabin.

“No, probably that drum was beaten by some of the native priests,” explained the hunter.  “The natives are very superstitious, and likely they took us for an evil spirit, and wanted to drive us away.”

“Then we’ll hustle along out of their sight,” said Tom, as he went to the pilot house to increase the speed of the airship, for he had been letting it drift along slowly to enable the adventurers to view the country over which they were passing.  A few minutes later, under the increased force of the machinery, the Black Hawk left the native village, and the crowd of frightened blacks, far behind.

The travelers passed over a succession of wild stretches of forest or jungle, high above big grassy plains, over low but rugged mountain ranges, and big rivers.  Now and then they would cross some lake, on the calm surface of which could be made out natives, in big canoes, hollowed out from trees.  In each case the blacks showed every appearance of fright at the sight of the airship throbbing along over their heads.

On passing over the lake, Ned Newton looked down and cried out excitedly: 

“Look!  Elephants!  They’re in swimming, and the natives are shooting them!  Now’s our chance, Tom!”

Mr. Anderson and Mr. Durban, after a quick glance, drew back laughing.

“Those are hippopotami!” exclaimed the old elephant man.  “Good hunting, if you don’t care what you shoot, but not much sport in it.  It will be some time yet before we see any elephants, boys.”

Ned was rather chagrined at his mistake, but the African travelers told him that any one, not familiar with the country, would have made it, especially in looking down from a great height.

They sailed along about half a mile above the earth, Tom gradually increasing the speed of the ship, as he found the machinery to be working well.  Dinner was served as they were crossing a high grassy plateau, over which could be seen bounding a number of antelopes.

“Some of those would go good for a meal,” said Mr. Durban, after a pause during which he watched the graceful creatures.

“Then we’ll go down and get some for supper,” decided Tom, for in that hot climate it was impossible to carry fresh meat on the airship.

Accordingly, the Black Hawk was sent down, and came to rest in a natural clearing on the edge of the jungle.  After waiting until the fierce heat of noonday was over, the travelers got out their rifles and, under the leadership of Mr. Durban and Mr. Anderson, who was also an experienced hunter, they set off.