Much to the surprise of both DuQuesne and Loring, their prisoner had not made the slightest move against them. He had thrown all the strength of his supernaturally powerful body and all the resources of his gigantic brain into the task of converting the atomic motors of the _Violet_ into the space-annihilating drive of his own race. This drive, affecting alike as it does every atom of substance within the radius of action of the power bar, entirely nullifies the effect of acceleration, so that the passengers feel no motion whatever, even when the craft is accelerating at maximum--and that maximum is almost three times as great as the absolutely unbearable full power of the _Skylark of Space_. The engineer had not shirked a single task, however arduous. And, once under way, he had nursed those motors along with every artifice known to his knowing clan; he had performed such prodigies of adjustment and tuning as to raise by a full two per cent their already inconceivable maximum acceleration. And this was not all. After the first moment of rebellion, he did not even once attempt to bring to bear the almost irresistible hypnotic power of his eyes; the immense, cold, ruby-lighted projectors of mental energy which, both men knew, were awful weapons indeed. Nor did he even once protest against the attractors which were set upon his giant limbs. Immaterial bands, these, whose slight force could not be felt unless the captor so willed. But let the prisoner make one false move, and those tiny beams of force would instantly become copper-driven tornadoes of pure energy, hurling the luckless body against the wall of the control room and holding him motionless there, in spite of the most terrific exertions of his mighty body. DuQuesne lay at ease in his seat; rather, scarcely touching the seat, he floated at ease in the air above it. His black brows were drawn together, his black eyes were hard as he studied frowningly the Fenachrone engineer. As usual, that worthy was half inside the power plant, coaxing those mighty motors to do even better than their prodigious best. Feeling his companion's eyes upon him, the doctor turned his inscrutable stare upon Loring, who had been studying his chief even as DuQuesne had been studying the outlander. Loring's cherubic countenance was as pinkly innocent as ever, his guileless blue eyes as calm and untroubled; but DuQuesne, knowing the man as he did, perceived an almost imperceptible tension and knew that the killer also was worried. "What's the matter, Doll?" The saturnine scientist smiled mirthlessly. "Afraid I'm going to let that ape slip one over on us?"