He did not remember exactly when the idea of killing Hervey occurred to him. Probably, though, it had been that day at Hermes Station, when the wrench had slipped from his grasp as he worked on the tower; it had drifted lightly down and struck Hervey a glancing blow on the helmet. They had laughed about it, and Hervey had said, "If we were under grav conditions, Joe, that probably would have conked me." It had been funny then, but it wasn't funny any more. Joe Berne watched Hervey all of the tim