Ahead of them, and on a higher level, there was now visible a series of swiftly-vibrating brilliant sparks. They filled a mere tiny spot in space. To the expert young airman they were guiding. Dave set the machine on a swift drift then climbed up several hundred feet. Now the sparks, intermittent but perfectly distinct, were clearer and nearer the faster they went.
“It’s a machine,” soliloquized Dave, “and it must be the Scout. If it is—clever Hiram! He doesn’t dare show the lights, for that man aboard wouldn’t let him. I can guess what he has done—the vibrator.”
Dave, with a perfect knowledge of all the parts and possibilities of the natty little Scout, was at home with every detail of the mechanism of the machine, and guessed what was transpiring. Later on his surmises were verified. The young aviation expert decided that his chum counted on his searching for him. He had loosed the top of the vibrator, probably sending it adrift.
If he awakened the suspicion of the passenger, he could readily make a pretence of watching the sparks jumping from one coil to the other, to see that all the cylinders were working right. Correct or not in his guess, those distant electric points of light were now a direct guide to the eager pilot of the Ariel.
“We’re getting nearer,” breathed the man behind him. “You think it’s the airship we’re after?”
“I am pretty sure of it,” responded Dave. “It’s a race, now, officer. This machine can overtake the Scout and outdistance it within the next half hour. Then the case is up to you.”
“Just get me in reach of Reddy Marsh,” spoke the policeman, “and I’ll do the rest.”
CHAPTER XII
A DESPERATE PASSENGER