Bob sweated, having only fractions of seconds in which to maneuver for the "yo-yo" could strike a fatal blow at the hauler too. It was ticklish work completely to nullify the "yo-yo's" speed. Bob used exactly the same method of catching the "yo-yo" on the blunt nose of the ship as a baseball player uses to catch a hard-driven ball in his glove—namely, by matching the ball's speed and direction almost exactly at the moment of impact. And now Bob's hours of practice paid dividends, for the "yo-yo" came to rest snugly, ready to be released again.

All this had happened in such a short space of time that the Saylor brothers must have had only a bare realization of what was going on. But by the time the "yo-yo" was flung at them again, this time with better calculations, they managed to put the firmly held asteroid between them and the deadly missile. But it was clumsy evasion, for the asteroid was several times as massive as the ship which was towing it, and its inertia was great. And as soon as the little ship came spinning back to rest, Bob flung the hauler to a new vantage point and again the "yo-yo" snapped out.

And this time—collision! Bob yelled as he saw the stern section of the Saylor brothers' ship crumple like tissue paper crushed between the hand. The dumbbell-shaped ship, smaller, and therefore stauncher due to the principle of the arch, wound up again, wobbling a little. It had received a mere dent in its starboard half.

Starre was chortling with glee. Queazy whispered, "Attaboy, Bob! This time we'll knock 'em out of the sky!"

The "yo-yo" came to rest and at the same moment a gong rang excitedly. Bob knew what that meant. The Saylor brothers were trying to establish communication.

Queazy was across the room in two running strides. He threw in the telaudio and almost immediately, Wally Saylor's big body built up in the plate. Wally Saylor's face was quivering with wrath.

"What do you damned fools think you're trying to do?" he roared. "You've crushed in our stern section. You've sliced away half of our stern jets. Air is rushing out! You'll kill us!"

"Now," Bob drawled, "you're getting the idea."

"I'll inform the Interplanetary Commission!" screamed Saylor.