"Yes, that's right, but I've geared--pulleyed, I mean--two of them up, so that they'll turn the other two at least twice their normal armature speed. And the simple electric motor works--" "--in reverse, too, doesn't it! If you turn it by mechanical means, it generates electric current!" "That's about it. I ought to get about five hundred volts from each, with the pulley ratio I'm using. And they're both connected in series, so--a thousand volts, I hope. Childish, isn't it--" There was sudden chaos above them. "Doug--" Terry dropped the last fan-blade to the floor. Doug pressed the switches, and the two electric motors spun into humming, whirring motion, driving the other two at a speed he knew might burn them out in minutes. Then he closed the Contraption's main switch, and pulled Terry and Mike bodily to him with one arm as he held tightly to Dot with the other. S-men swarmed down the cellar stairs. CHAPTER XXI A dozen men clad in white uniforms of the S-Council surrounded them, and there were weapons in their hands. Senior Quadrate Blair understood. Partially, he understood. He had been reading a banner headline, and then suddenly--suddenly there had been an indescribable moment of utter dark, of awful timelessness--and cold. And there was still the cold, tangible and fluorescing in a green-blue flame about him. Through it he could see the white blurs--the men in white. S-men.... "Lisa--" He felt her beside him, crushing their two sons to her trembling body. He could see their faces, then--upturned to his, pleading, afraid. "The change. Somehow my counterpart, my imposing alter-ego has succeeded, Lisa! He has found his way back, and in so doing he has returned the four of us...." And then the green glow and the cold was gone, and there was no more time to speak. "Stand where you are! You have only to move to--_Madame Blair_!" The leader of the white-uniformed band had half-succeeded in masking his initial amazement, but now the surprise on his heavy face was a naked thing. The others stood as statues to each side of him. There was an awful moment of silence, and the weapon-muzzles held steady, even if the dozen hands that gripped them were momentarily incapable of flexing trigger-fingers. And then the Senior Quadrate had found his full voice. "There has of course been some error. S-men do not enter the home of a Senior Quadrate--" And Lisa's voice cut across her husband's. "They--Douglas, these aren't--aren't S-men! I recognize him--the leader! Mylor Kuun...."