And what had become of Spangler. Where had he gone? And why had he gone?
That was a conundrum, and Matt had no time to give to conundrums just then.
Josh, eager to do all he could, was tugging and straining at the rocks.
"It won't do, Josh!" shouted Matt. "Run for those boulders at the side of the road and wait for me."
To think quickly in an emergency was Motor Matt's long suit. Many a time his cool head had helped him out of a bad difficulty.
While he was shouting to the boy he was running back to the car. Snatching the wrench from where he had dropped it in the rumble, Matt went to work with lightninglike energy on the cap of the gasoline-reservoir.
In record time he had the cap off. Bending down he scooped up a handful of sand from the road and dumped the most of it into the reservoir, then, as quickly as he had removed the cap, he replaced it, flung the wrench into the car and jumped for the boulders.
Hardly was he back of the big stones that clustered along that edge of the valley, when the Red Flier shoved her nose through a cloud of dust and came scorching onward.
Brisco must have been astounded to see the runabout, deserted and at a halt in the road. The way, of course, was blocked for him as well as for the runabout, and he halted the Red Flier at a good distance from the other machine, leaped out and came running to the other car.
The stones in the road probably gave him a pretty good idea of what had happened, for he immediately began looking around him as though expecting to see some one—possibly Matt and Josh.