A cry from another section of the sphere made them turn. It was the professor's voice.
"Here they come," he shouted. "Hundreds of them."
Carlson and Grimm dashed through a doorway in the direction of the cry. Ro followed, entering a spacious room. He was taken back by the intricate machinery he saw. There were countless numbers of dials and levers, gauges and indicators.
Carlson and Grimm took their places at tiny portholes. Ro found an unoccupied post and peered out. He saw a mass of grey bodies charging toward the sphere. There were more rat men than he'd ever seen at one time before. They seemed to be climbing over one another as they raced from the forest.
A sudden whirring of machinery within the sphere caused Ro to turn from the porthole. The three Earthmen were working levers and twisting dials frantically. Additional portholes appeared in the sides of the sphere. Long tubes rose on folding legs from the floor and slid through the openings.
"Take aim," the professor shouted in a commanding voice.
The whirring within the sphere grew louder. The floor seemed to quiver underfoot as giant motors generated energy.
"Fire!"
The entire sphere shuddered. Earthquaking explosions sounded outside as charges of force left the tubes to expel their power on the grey mass in the clearing.