Suddenly his arm shot out of the sling, and as suddenly Hiram, though with a wince, swung it around once or twice, and the three splints holding it cracked and split audibly.
"Hey, Hiram!" gasped Dave.
"S-sh!" uttered his assistant warningly.
Hiram ran his free hand down into his pocket. He drew out the big pocket knife he carried. It was more of a tool than a whittling toy, for he used it in tinkering about the airship.
With his teeth, Hiram opened its largest blade. He gave a slash at the cords surrounding his other arm and his feet. Then he leaned over towards Dave. A few deft strokes of the keen blade, and Dave, like himself, was free.
"Easy," he whispered, as Dave started up. "I'll watch Dawson. You get into the pilot's seat."
"Good for you, Hiram!" whispered back the young aviator, fairly thrilling with the excitement of the moment.
Dave took in every detail of the mechanism before his eyes. He made sure of no faulty start.
"All ready," he announced after a minute or two.
"Good-bye!" spoke Hiram, with a gay bold wave of his hand in the direction of the sleeping, Dawson.