They could see the strain that was put upon the giant in his swelling veins and the muscles of his hands and arms, for they stood out knotted, and in bunches. With all his great strength it was all Koku could do to hold the pump from tearing completely loose.
"Quick, Ned!" cried Tom. "Shut off all the power! Stop the pump! I've got to bolt it fast. Start the gas machine, Mr. Damon. You know how to do it. It works independent of the motor. You can let go in a minute, Koku!"
It took but a few seconds to do all this. Ned stopped the main motor, which had the effect of causing the propellers to cease revolving. Then the airship would have gone down but for the fact that she was now a balloon, Mr. Damon having started the generating machine which sent the powerful lifting gas into the big bag over head.
"Now you can let go, Koku," said Tom, for with the stooping of the motor the air pump ceased plunging, and there was no danger of it tearing loose.
"Bless my court plaster!" cried Mr. Damon. "What happened, Tom?"
As the giant arose from his kneeling position the cause of the accident could easily be seen. Two of the big bolts that held down one end of the pump bed-plate to the floor of the airship, had cracked off, probably through some defect, or because of the long and constant vibration on them.
This caused a great strain on the two forward bolts, and the pump started to tear itself loose. Had it done so there would have been a serious accident, for there would have been a tangle in the machinery that might never have been repairable. But Koku, who, it seems, had been watching the pump, saw the accident as soon as it occurred. He knew that the pump must be held down, and kept rigid, and he took the only way open to him to accomplish this.
He pressed his big hands down over the place where the bolts had broken off, and by main strength of muscle he held the bed-plate in place until the power was shut off.
"Koku, my boy, you did a great thing!" cried Tom, when he realized what had happened. "You saved all our lives, and the airship as well."
"Koku glad," was the simple reply of the giant.