Ben agreed that if the air-ship could be inflated it would be much better to fly to land in her than to set out under the tropical sun in an open boat, not knowing where they might land.
The camp was so arranged that night that the treasure was placed near to the boys and Ben, while the three members of the dirigible's crew, her engineer and Constantio slept at some little distance.
Had the boys seen the gleam that had come into the inventor's eyes at the discovery of the boat they would not have been so trustful of him when he volunteered to take the middle watch of the night. As it was, however, they little imagined the plot that had formed in the fellow's head. While the boys and Ben slumbered, however, he drew aside the engineer and Wells, the red-headed sailor, and the three rapidly stocked up the boat with water from the spring in kegs and jars taken from the dirigible and laid in a supply of provisions. Then they awakened the other two men and explained to them in low whispers the plan to escape from the island they had formed.
"We will get all the treasure and divide it," whispered the cunning inventor. "If the boys wake while we are getting it to the boat, don't hesitate to attack them. We are stronger in numbers and can beat them off."
The other two readily agreed, more particularly as the inventor told them that it was the boys' intention to keep all the treasure for themselves in the event of their getting ashore in the dirigible. Before the boat had been found the inventor had been willing enough to aid the boys, but with the discovery of that means of escape his plans had undergone a change. He saw a way to appropriate the entire mass of treasure.
CHAPTER XXV.
THE FIGHT ON THE ISLAND.
Silently as cats the plotters approached the pile of treasure sacks when they judged that the time was ripe for their raid on the valuables. Constantio, who was a coward at heart, had taken his station by the boat so as to be the furthest away from danger should the boys be aroused.
With a beating heart he waited the appearance of the first heavy bag of treasure. At last the engineer and one of the sailors came in sight dragging it over the top of a sand dune.
"Phew, that's heavy," exclaimed the sailor, who was our red-headed friend, Wells, setting the bag down with a sigh. "How far is it from the camp to this boat, Mister Concertina?"