“Turn on your power!” shouted the professor.
The bell for “full speed ahead” rang sharply out. At the same instant the propeller began to whir.
As it did so, several Indians, who, in their onrush on the dirigible, had clambered upon it, were thrown off in all directions. They rolled over and over, like so many footballs. This made the others pause an instant, and in that instant the dirigible rose from the ground.
But the chill night air had condensed the gas, and she rose slowly. Before more than five feet had been gained in her upward rise, the Indians recovered from their amazement and charged like a pack of furies.
“Flat on your faces!” shouted the professor, as a shower of arrows pinged and pattered in the framework of the craft.
They obeyed the command, and then Nat saw the queer gun brought into use. The professor raised it to his shoulder and pulled the trigger.
Instantly a stream of colored balls, like those that issue from a Roman candle, poured from the bell-like muzzle. But almost simultaneously with their discharge, they burst with sharp reports, and the whole air became impregnated with a black, all-obscuring smoke as thick as a London fog.
The dense clouds spread on every side, completely obscuring the dirigible from the view of the Indians below. Higher and higher she rose, while below her the dense smoke veiled everything like a curtain. Nat caught a whiff of the vapor, and it made him cough and choke.
“I’ll bet those Indians aren’t enjoying it,” he thought to himself. “So that was what that queer gun was.”
In a few moments they were high above the tree-tops, and the professor ordered the lights turned on. A switch was pushed over by Mr. Tubbs in the pilot-house, and the Discoverer blazed out with incandescents like an illuminated battleship. For a few seconds nothing much was done but to exchange congratulations. No one was hurt, and not an arrow had pierced the gas bag. This was accounted for by the fact that the Indians, not understanding how vulnerable that part of the craft was, had confined their volleys to the occupants of the lower structure.