But that is nothing. Tell Maringy and Euphroysne to do it. Net a ship and bring it here. Bring it down gently. You will have to kill the men in it, of course, but do it mercifully. Then let them bring me the robots. Use the green flame on one or two—the rest will follow, I’ll warrant you.” The hill behind where the old house had stood trembled. A circle of pale green light gleamed on its breast. It dimmed and where it had been was the black mouth of a tunnel. An airship, half rocket, half winged, making its way to New York, abruptly drooped, circled, fell gently, like a moth, close to the yawning mouth of the tunnel.

Its door opened, and out came two men, pilots, cursing. There was a little sigh from the tunnel’s mouth and a silvery misty cloud sped from it, over the pilots and straight through the opened door. The pilots crumpled to the ground. In the airship half a dozen other men, slaves of the robots, slumped to the floor, smiled, and died.

There were a full score robots in the ship. They stood, looking at the dead men and at each other. Out of the tunnel came two figures swathed in metallic glimmering robes. They entered the ship. One said: “Robots, assemble.”

The metal men stood, motionless. Then one sent out a shrill call. From all parts of the ship the metal men moved. They gathered behind the one who had sent the call. They stood behind him, waiting.

In the hand of one of those who had come from the tunnel was what might have been an antique flash-light. From it sped a thin green flame. It struck the foremost robot on the head, sliced down from the head to the base of the trunk. Another flash, and the green flame cut him from side to side. He fell, sliced by that flame into four parts. The four parts lay, inert as their metal, upon the floor of the compartment.

ONE of the shrouded figures said: “Do you want further demonstration—or will you follow us?”

The robots put heads together; whispered. Then one said: “We will follow.”

They marched into the tunnel, the robots making no resistence nor effort to escape. They came to a place whose floor sank with them until it had reached the caverns. The machine-men still went docilely. Was it because of curiosity mixed with disdain for these men whose bodies could be broken so easily by one blow of the metal appendages that served them for arms? Perhaps.

They came to the cavern where Narodny and the others awaited them.