"Watch, Henri! Are they pumping?" cried Frank.
"Yes!" said Henri. "Now—now—now is your time, Francois!"
Frank hesitated the fraction of a second.
"If it meant killing them, I could not do it," he said, solemnly. "But they are all out of the airships. Now!"
On the word he closed the circuit he had made by connecting the loose ends of the wire he had carried from his petrol filled hole to the two batteries he had brought from the car. He had broken the circuit at the other end, leaving the two wires separated by the fraction of an inch, and cunningly held in place. The result was a spark—or would be, if he had not erred.
And he had made no mistake! For as he closed the circuit, he saw a flash of flame at the spot where he and Henri had dug the hole into which the petrol had flowed from the barrel they had opened. The spark had fired the explosive gas that results when petrol is mixed with air. The flame ran along the shallow trench, and, amid a chorus of shrieks from the Germans who scattered in all directions, the fire reached the barrel. In a moment there was a loud explosion. The flame flew to the other barrels—the whole neighborhood of the barrels, owing to the mixture of the petrol and the air, was then filled with an explosive and inflammable gas.
There was a great flash of flame, broken by a dozen sharp reports as one barrel after another blew up.
And still, though the Germans were flying in all directions, plainly visible in the light of the blazing gasoline, the real success of Frank's plan hung in the balance. But then what he had calculated happened. The flame ran through the lines of hose. And a moment later two great shafts of flame marked the spread of the fire to the helpless monsters of the air. There was no chance to save them. Indeed, even the Germans had no other thought than to save their own lives. Their raid, whatever its ultimate object, was ruined and two vessels of the great air fleet of the Kaiser were destroyed.
For a moment after the final catastrophe the two scouts stayed, caught by the wonder and the magnificence of the ruin they had wrought. But then Frank cried out,
"Come on! We haven't a moment to lose! They'll know that that was no accident! Some came running this way. They'll find the wires! And then they'll know. The wires will bring them here. Hurry!"