The aeroplane was now far below the dirigible, which was soaring at a height of two thousand feet. At such an angle it was impossible for those on board to use their rapid-fire gun, and Frank, setting the Golden Eagle's rising planes, soared rapidly along at an elevation of about two hundred feet.
By the time the men on the dirigible had got her round, the Golden
Eagle was two miles ahead of the gas-suspended craft.
"We've escaped them," cried Harry.
"Not yet," said Frank; "don't holler till you are out of the woods. They know now we've got the treasure and they are not going to give up the chase as easily as all this."
From time to time the dirigible, which was not gaining on the Golden Eagle, fired a shot from her forward gun, but the dipping, scudding aeroplane afforded a poor mark and, moreover, the deck of a dirigible at full speed is not the steadiest place in the world. So after a few attempts more to wing the swift aeroplane, the crew of the dirigible gave the effort up and turned all their attention to getting every ounce of speed out of their craft. With sinking hearts the boys realized that she was gaining on them.
Hour after hour, above the glassy Sargasso Sea, the battle went on, the aeroplane ducking and diving and gliding and skimming whenever the dirigible got a good chance to send a fatal projectile into her.
From time to time, also, Ben got a chance to send a bullet crashing into the dirigible's gas-bag, and from the actions of the men aboard her they were evidently badly worried by this. However, as Ben knew, the gas-bag of the dirigible was constructed in sections and the gas manufactured by Constantio was so buoyant that if even one section remained intact it would still serve to sustain the dirigible in the air.
But no fight of such a character can endure long. Sooner or later one or the other of the combatants is bound to succumb, and so it was in this case.
Just as Frank was making a dive to avoid, for the twentieth time, getting within range of the dirigible's gun, a skillfully aimed projectile came crashing through the Golden Eagle's gasolene tank. The fluid poured out in a flood.
A few minutes later the engines ceased to revolve and the aeroplane was compelled to descend, Frank driving her down in a long arc that brought her to the surface of the water without accident.