There came another flash, but they had gone on past the place where the man's face had been observed, and no other foes were now revealed by the glare from the sky.
"There's one thing we ought to do," said Ned, after the House on Wheels had rumbled on a little farther, the grade being steeper now.
"What is it?"
"Put out those lights back of us. They only show us up to those who may be watching."
"That's right," agreed the young inventor. "Go in and douse 'em!"
At the same time he reached forward and cut the switch that controlled the illumination of his dashboard. This left the auto with but the bright headlamps glowing, and they kept any one who might be in front of the auto from seeing anything of the occupants of the driver's seat.
In the darkness Ned sat beside his chum. The House on Wheels was being driven on. Ned was about to ask Tom if he did not want to be relieved for a while when there came a sudden sharp crack from the bushes on the left of the road. At first Ned thought it was a preliminary to a burst of thunder. A moment later he knew it had been a rifle shot.
Then came several more reports, and one bullet, fired from ambush, shattered a window back of the two who had dared to try to solve the mystery of Dismal Mountain.
CHAPTER XIX
PRISONERS