Charge after charge was poured into the attacking rat men.
Ro leaped back to the porthole. He saw giant craters opening in the ground. Hoarse screams of pain and terror reached his ears. Scores of Oan were literally torn apart. Others disappeared completely. Those of the attackers who lived retreated in disorder. Ro noticed that one of the retreating Oan carried a ray gun.
"Cease fire," shouted the professor.
Carlson and Grimm turned from their guns laughing.
"They won't be back," chuckled Grimm. "They'll keep running for a week."
Ro moved silently to the post Carlson had occupied. He picked up the ray gun the Earthman had laid aside.
"What do you want with that?" asked the professor. "The battle is over. There won't be any use for ray guns now. We've beaten them."
"How does it work?" Ro asked grimly. His face was hard with determination.
The professor was puzzled, but explained the workings of the gun. He finished his explanation with, "But why?"
Ro walked to the door.