Less than a mile away, Professor Thornton stood at his window in the observatory watching for the burst of light which, if it came, would indicate to him that the Ring had started upon its flight into space. He had already been to the equatorial-room and revolved its dome until the mouth of the great telescope pointed in the general direction which the Ring would presumably take. Medusa was almost at the zenith, her pale-green light somewhat dimmed by the light of the full moon, which blazed in the sky a few degrees to the east of the asteroid. He glanced at the clock. It was already quarter to nine. Perhaps Hooker might not start on time, after all. Something might go wrong with the complicated anatomy of the machine; some unexpected delay might occur--in which event he, Thornton, would not be notified and would wait at the telescope vainly searching the heavens while, perhaps, the Ring would suddenly start on its flight--the direction slightly altered from that as originally planned--and he would miss it altogether. So he returned to his office to observe with the naked eye the departure of the Ring, note its general direction, and make sure of getting it in the finder of the telescope. For Thornton had never doubted that the Ring would start. He had known Hooker, boy and man, for nearly thirty years, knew that he was a practical as well as a brilliant scientist, and, when Pax had threatened to knock the earth topsyturvy, had himself been the one to rout the professor out of his scholastic seclusion on the Appian Way in Cambridge, and stimulate him to those investigations which shortly resulted in the discovery of the valley of the Ring in Ungava and the navigation of the air-craft back to the United States. Thornton did not question the ability of Hooker and his comrades to navigate space in the great machine, or the power of the lavender ray to destroy Medusa or any other heavenly body. What he feared was the unknown factor of chance, always arising when an experiment is hazarded under new conditions. What did they know of space? Would their liquid-air tanks accomplish their purpose? What would be the effect of the complex and opposing forces of attraction to which, once outside the sphere of the earth's gravitation, this new man-made meteor would be exposed? Could the Ring be "turned" so as properly to alight? Would it turn? Would the human organs function under these extraordinary artificial conditions? Would, in fact, the brain work properly or logically when no natural premises were left from which to reason? Well, they would see! But the Ring would start! Oh, yes, it would start--and its departure would be caught on the film of the automatic moving-picture astronomical camera attached to the big telescope--provided, of course, that he succeeded in following its meteoric flight.