Tom had ordered a tank set up in his laboratory to test the unit. The tank was filled chest-deep with water, and the ion drive was mounted on a unitrack running the length of it. Tom set up his control board alongside, with the main power switch within easy reach. The drive unit was connected to the board by a suspended cable.
“Boy, this’ll be like playing with a speedboat in a bathtub!” Tom thought with a chuckle as he changed into swim trunks.
THE CAISSON CLUE 63
He climbed into the tank and slid the drive unit to one end of its track. Then Tom metered out power slowly. With a gentle whoosh, the ion-drive unit whizzed along the unitrack to the other end of the tank.
“Not bad,” Tom muttered, a pleased grin on his face. “Now I’ll rev it up a little.”
He slid the drive unit back to starting position, then opened the switch wider.
He had just started across the tank himself when suddenly he became powerless to move.
Tom was pinned helplessly against the wall of the tank by the powerful water-jet exhaust! And the control switch was beyond his reach!
CHAPTER VII
PORPOISE TAG
“GOOD grief! I’m trapped!” Tom squirmed desperately in a vain attempt to free himself.
The ion-drive unit had hurtled to the far end of the tank at the first flick of power. But its exhaust tube was still jetting out a current of water with stunning force. Tom could feel the near-crushing pressure against his chest, even the full length of the tank away!
“H-h-help!” Tom gasped.
Moments dragged by with agonizing slowness. Tom felt as if his last ounce of breath were being squeezed out by the viselike pressure.