A whirl of the biplane sent the man banging against the side of the seat till his teeth rattled.

“Strap him in,” called out Hiram, “if he don’t want to get a spill.”

“Oh, my! Stop! Please stop! Let me out!”

Meantime Elmer had snapped the belt in place. It was well that he had acted speedily. The Comet made a switch just there which caused the involuntary passenger to tremble with terror, yell outright, and crouch back in his seat.

Hiram directed a smooth volplane and made an even spurt of speed on a set level. This gave the intruder a chance to steady his nerves and regain his breath. He was still, however, big-eyed and chattering. The young pilot dared not direct attention from his task of running the machine, but he managed to turn his face sideways so as to give Elmer a significant glance. The latter half smiled as he understood what was on the programme.

“Now, see here, officer,” spoke Hiram, past his shoulder, “I can’t give you any further attention than to tell you what to do. If the machine tips——”

“Is there danger?” gasped the overcome constable. “Say, please go down! Easy, you know! P-please-p—please!”

“You had better show some sense,” retorted Hiram, with pretended sternness. “There is always danger of a spill. Don’t help it any.”

“N-no, I won’t,” chattered the officer. “I—I’ll do just what you tell me.”

“Then sit still and keep still. Elmer, get him into that airman armor. He’s pretty bulky, and if we take a flop——”