Their leg-joints bent; their bodies swayed. The note seemed to move now here and now there about the chamber, and always following it, grotesquely. Like huge metal marionettes, they followed it. The music ended in the crashing note. And it was as though every vibrating atom of the robot bodies had met with some irresistible obstruction. Their bodies quivered and from their voice mechanisms came a shriek that was hideous blend of machine and life. Once more the drone, and once more and once more and then, again, the abrupt stop.

There was a brittle crackling all over the conical heads, all over the bodies. The star-shaped splinterings appeared. Once again the drone—but the two robots stood, unresponding. For through the complicated mechanisms which under their carapaces animated them were similar splinterings.

The robots were dead!

Narodny said: “By tomorrow we can amplify the sonor to make it effective in a 3000 mile circle. We will use the upper cavern, of course, it means we must take the ship out again. In three days, Marinoff, you should be able to cover the other continents. See to it that the ship is completely proof against the vibrations. To work. We must act quickly—before the robots can discover how to neutralize them.”

IT was exactly at noon the next day that over all North America a deep inexplicable droning was heard. It seemed to come not only from deep within earth, but from every side. It mounted rapidly through a tempest of tingling crystalline notes into a shrill piping and was gone. Then back it rushed from piping to drone; then up and out and down. Again and again. And over all North America the hordes of robots stopped in whatever they were doing. Stopped—and then began to dance—to the throbbing notes of that weirdly fascinating music—that hypnotic rhythm which seemed to flow from the bowels of the earth.

They danced in the airships and scores of those ships crashed before the human crew could gain control. They danced by the thousands in the streets of the cities—in grotesque rigadoons, in bizarre sarabands; with shuffle and hop and jig the robots danced while the people fled in panic and hundreds of them were crushed and died in those panics. In the great factories, and in the tunnels of the lower cities, and in the mines—everywhere the sound was heard—and it was heard everywhere—the robots danced ... to the piping of Narodny, the last great poet . . . the last great musician.

And then came the crashing note— and over all the country the dance halted. And began again . . .