With a series of chug-chugs the machine darted ahead. The hunter urged his horse on and the adventurers were once more moving toward the hidden mine. It was going to be a bright, moonlight night, as could be told by the silver disk that was already rising above the trees.
“We’ll hardly need the gas lamps,” observed Ned.
“But it’s better to have them,” remarked Jerry, who had been selected to do the steering.
Leaving the broad and level road that led south over the plains, the adventurers headed due west. In a little while it was evident that the machine was going uphill, for the motor began puffing laboriously, and Jerry shifted the gear to first speed.
“We’ve struck the foothills,” observed Nestor. “In a short time we’ll be going up the mountain. Then, look out!”
Broswick rode along just behind the machine on his horse. The animal was a steady trotter and managed to keep up to the auto, which was obliged to move slowly, as it had quite a heavy load on a steep grade.
For several hours the machine kept going. All the while the ascent became more and more steep until, at length, the adventurers found themselves well above the foothills and among the mountains.
“We’ll keep on until about ten o’clock,” said Nestor. “Then we’ll camp for the night. We must get some sleep or we’ll be all tired out.”
Up, up, up went the auto. After quite a climb a small plateau or level stretch was reached, and there the going was easier. Jerry took advantage of it to run on the second gear. It was quiet, save for the mournful hooting of an owl now and then, as the machine made little noise, and no one felt like talking. All at once there came from the rear seat a strange sound.
“What’s that?” asked Jerry.