The time agreed upon was immediately after the first sign of the rising moon, Phobus, above the horizon. Explaining the various features of the _Sphere_ as vaguely as possible, Robert watched closely for the first glow of the planet’s little moon. The several windows in the western end of the building offered a fair view of the horizon in that direction. As the fateful hour approached, Robert determined to get the _Sphere_ outside the building in some manner, in order that he would be best prepared to make a dash to the palace at the proper moment. Accordingly, he informed the Martian with him that he intended to take the _Sphere_ outside for a trial flight before leaving it, asking him whether he desired to accompany him or not. He was hoping, of course, that the Martian would say “no.” He did not wish to seem desirous of getting rid of him for fear that his suspicion would be aroused. As Robert had half expected, however, the Martian informed him politely that it was the emperor’s wish that the _Sphere_ not be taken out of the building for the present. It was plain that Robert would have to resort to strategy to carry out his plans. Accepting the Martian’s statement with apparent readiness and good nature, he remarked that he could just as well test the _Sphere_ some other time, and prepared as if to leave it. He succeeded in maneuvering so as to follow the other out, though the Martian preceded him with evident reluctance. Upon reaching the exit in the outer shell of the _Sphere_ the spy turned as if minded to request Robert to precede him there. Realizing that it was now or never, Robert leaped upon him suddenly, delivering a sharp blow to the spy’s jaw that sent him reeling down the few remaining steps and through the open trap on to the floor of the building. Simultaneously with the Martian’s cry of baffled rage, Robert slammed the trap-door shut and raced up the steps. A moment later he had the gyrostats in motion. His heart sank, though, as he saw all three of the Martians tugging at the massive door that stood between the _Sphere_ and freedom. Already it was sliding to with their efforts. His escape was cut off! For a moment Robert was tempted to press into service the automatic that reposed in a locker but a few feet away. But the thought of firing upon them in cold blood was repugnant to him. Apparently the Martians were unarmed. During their sojourn on Mars, Robert and his companions had not found out what kind of weapons the Martians used. Two of the Martians remained inside the great door, shouting to him to come out of the _Sphere_. The third had slipped out, no doubt to inform the emperor of his attempted escape.