"Maybe they made a mistake----" commenced Sam, when Dick, who was examining the ground, uttered a cry.
"Here are the tracks of the rubber tires!" exclaimed the eldest Rover boy. "See, they pushed the plank aside and steered right for the bridge!"
"But did they get over?" asked his brothers.
"I suppose so. Wait, I'll go over and see."
Lantern in hand, Dick crossed on the beams of the wooden bridge. On the opposite side he saw the same tracks of the tires in the dust and dirt.
"They must have thrown it into place to cross and then taken it up again, so that they couldn't be followed,--that is, in a carriage, or an auto, or on horseback."
"Yes, but they can't stop a biplane!" cried Sam, eagerly. "And this must have taken time to do! We must be close behind them!"
"Let's get right after 'em!" put in Tom, and all three ran once more for the _Dartaway_, and soon the quick explosions of the motor sounded on the night air.
If the boys had been excited before, they were more so now, for they realized that the touring car at the best could be but a few miles away. Could they catch up to it before those running the machine had a chance to slip them in the darkness?
"They must have their lights lit," said Dick. "They'd not dare run without them. Look and see if you can't spot their headlights. Their taillight we smashed with a pistol shot."
On and on swept the biplane. As the late moon came up higher, the way became brighter, until they could distinguish the road below quite plainly. But nothing like a touring car came into view.
"They must have had more time than we thought, or else they ran mighty fast," remarked Dick, after several miles had been covered.
Presently they saw two bright lights coming towards them, down on the road. At once Dick shut off the power, and allowed the biplane to come down in the centre of the highway. Then Tom waved the lantern, and at the same time all three lads took hold of their pistols.
It was a runabout that was coming up, an old affair, carrying two men that looked like farmers.
"Hello, what's this, a hold-up?" cried one of the men. "By gum! if it ain't an airship!" he gasped, as his machine came to a standstill in front of the _Dartaway_.
"We'd like some information," said Dick, stepping forward and holding up the lantern. "We are looking for a big enclosed touring car that came this way. Did you meet it on the road?"