cylinders of the motor. The pump had torn partly away from its fastenings. Kneeling there, pressing down on the bed-plate with all his might, Koku was in grave danger, for the rod of the pump, plunging up and down, was within a fraction of an inch of his head, and, had he moved, the big taper pin, which held the plunger to the axle, would have struck his temple and probably would have killed him, for the pin, which held the plunger rigid, projected several inches from the smooth side of the rod.
"Koku, what is the matter? Why are you there?" cried Tom, for he could see nothing wrong with the machinery now. The airship was sailing on as before.
"Bolt break," explained the giant briefly, for he had learned some engineering terms since he had been with Tom. "Bolt that hold pump fast to floor crack off. Pump him begin to jump up. Make bad noise. Koku hold him down, but pretty hard work. Better put in new bolt, Mr. Tom."
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
