Frank leaped out.
"Turn the car around first," he said. Henri obeyed. "Now try your starter. Cut out the motor and then see if she starts quickly."
Henri, mystified, obeyed.
"Why?" he asked.
"Because when we want to start, we may have to do it in an awful hurry," said Frank. He searched the road for a moment. "Run her back a few feet to where that big tree is. It's darker there than anywhere else around here. All right, that's far enough. We'll have to take the chance of something coming along while we're gone and bumping into her but I don't believe there's much risk of that. Now, come on! And quiet! We've got to get up to that place without being seen."
Cautiously they approached the house. No lights showed in any of its windows; the place looked deserted. Indeed, all around it were traces of hasty flight. It was a wayside inn, of a type common always in France, commoner than ever since the spread of the craze for automobiles and motor touring. Suddenly Frank stopped.
"Wait a minute for me," he said. "I've got to go back to the car. I ought to have thought of it before."
"What do you want?"
"Batteries. I saw a coil of wire in the car and I want that, too. And there must be batteries. A car like this would carry everything needed for small repairs, wouldn't it?"
"Yes. I think you'll find them under my seat."
Frank was back in less than five minutes.
"All right," he said. "I don't know whether we'll have time to do what I want or not, and whether I'll be able to do it, anyhow. But it's worth trying. Now come on past the house. Easy! This is the hardest part of it."
They slipped by. However, Frank uttered a suppressed exclamation as soon as they had done so. Before them, on the right of the road was a field easily two or three times as large as the ordinary French field. As a rule the land in France is split up into very small sections, closely cultivated. But here was a cleared field as large as those commonly seen in England or America, with no fences for perhaps a quarter of a mile in any direction. Henri turned to look back at the inn.
"They're still signalling from there—and look! There are two lights now, instead of one, above!"
These lights were still some distance away. Frank studied them. Then he led the way into the field.
"I thought so!" he said, with suppressed triumph in his voice. "Do you see those barrels over there toward the inn? There's petrol in those—or I'll eat my shirt!"
"And if there is?" said Henri. "What then?"
"Can't you guess? What do you suppose those lights mean?"
"Never! They wouldn't flash that way. They'd have to be in a different position entirely. No. Dirigibles!"
"Zeppelins?"
"Perhaps. Perhaps Parsevals or Schutte-Lanz airships. I think Parsevals, for they need gasoline. And Zeppelins could fly from Brussels or Liege, almost from Cologne—oh, I have it! That's why they need petrol!"
"Why?"
"They haven't flown over Belgium at all! They are from the sea!"
"Oh—so that they could come secretly, and not be seen as they passed over Belgium?"
"Yes. If they flew over Belgium they would have to cross some territory that the Germans do not hold, and word would go to Antwerp and from there to the army here. Now quickly! They will be here soon. They are coming nearer every minute."
They went to the barrels as fast as they dared. There was nearly a score of them, all close together. Each had a tap, and it was proof enough that they contained petrol to open the tap of one. The smell identified them beyond any doubt whatever.
"Come on, and help me dig a hole," said Frank. He dropped to his knees, and began scooping out the soft earth with his hands. Henri fell to with a will, though he was sadly puzzled. But when the hole had been dug to a depth of perhaps two feet, and Frank began to hollow out a trench toward the barrels he began to understand. And as soon as he did, he worked as hard as Frank himself, careless of torn finger nails and bleeding hands. They carried the trench to the foot of one of the barrels, and Frank turned the tap. The gasoline ran out into the trench, and flowed to the hole. Frank ran back to the hole.
"Stop it when I give the word," he said. "Now!"
Then he was busy with the copper wire he had brought from the automobile for several minutes. The wire had been carried either to repair cut telegraph or telephone wires, or to serve as the conductor for a field system of lighting. But whatever its original purpose had been, Frank was thankful now that he had found it. He worked fast, and was satisfied at last.
"Now a little straw and a few twigs over the hole and the trench—and the sooner they come, the better!"
"Yes, the sooner, the better!" echoed Henri, tremendously excited, now that he understood, even if rather vaguely, what Frank planned. "Vive la France! A bas les Allemands!"
As they went back toward the road Frank trailed the wire behind him in two lengths. And when they reached the road, he dropped into the ditch, and was busy for some minutes.
"Now if it only works!" he said. "Perhaps it will; perhaps it won't. But it can't do any harm. That's certain."
"They're coming closer. I think I can see their shapes now—and there are two of them," said Henri. "Do you see?"
For a moment Frank could not. Henri's eyes were sharper than his. But then he did make out vaguely two immense shapes that were coming through the air. Soon, too, the faint hum of their powerful motors made itself heard.
"Zeppelins and big fellows, too," said Frank. "All the better!"
He wondered if his plan would work, and if he would be able to carry it out. If, in the final test, would he dare to do what he had tried to arrange? Time enough to think of that when the moment for decision came. And meanwhile there were a hundred things that might happen to ruin his plan. There was nothing to do now but wait. But every moment of waiting brought the climax nearer. The hum of the motors of the airships rose louder on the quiet air, broken only by the faint and distant mutter of the battle that was still being fought miles away. It sounded now like the buzzing of a swarm of bees, magnified a thousand times. And then the field was full of men, rushing from the inn. He wondered how they could have been concealed there. But such wonder was idle, and he did not think of it. Instead he watched keenly. First one monstrous aerial battleship came to rest on the earth. At once the men in the field surrounded her, seizing the ropes that were flung out, and made her fast.
There was a good deal of noise. Men were calling in German of course. But soon order was restored, and the only voices were those giving commands. Suddenly Frank's face lighted up.
"Did you understand, Henri?" he said. "The men in the field are to be the crews for the fighting. They have sailed here with only enough men to steer them. And now all are ordered out, to stretch their legs!"
"Yes, I heard that order," said Henri.
"Now keep your eyes glued to them. What are they doing?"
They listened and watched intently.
"Just as I thought," said Frank. "See, they are going to fill the tanks. There, they are attaching hose. And they have a pump—they surely must have a pump, to send the petrol uphill!"
Meanwhile the other airship had come down, on the other side of the barrels, and there as nearly as they could judge, the same procedure was carried out.
"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!"