Actually, the spacecraft was quite close to the shape of a hen's egg. It stood upon its smaller end, supported by four heavy vanes that held the drivers. Above them, the bulge of the hull swelled out in the gentle curve, and about the place where the soft-boiled-egg gourmet cuts the top off of his breakfast food, the hard metal stopped and the upper curving dome of the spacecraft was made of window. Not a clear expanse of glass, but more like the greenhouse roof. Small facets set between rigid girders in a neat and efficient pattern. The girders were reasonably heavy, because each one held shutter flaps that would snap closed if the pane of glass beside it became pierced because of contact with cosmic detritus. At the very top of this dome the glass was a smooth sheet, polished and unbroken. This section, a full ten feet in diameter, was optically perfect. For through this dome of glass the spacecraft was aimed. If the stars actually were where they looked to be to the eye, there would have been something less of a problem. A set of precision cross-hairs set along the axis of ship's drive could be used as a line-of-sight aiming point. Like a ship near the shore, the bow could be aimed at the pier, the power set, and then the rest would take care of itself. But stars move in their heavenly way. A poor ten to fifty miles per second can become a rather awesome gulf after four years. Alpha Centauri is a little more than four light years away. That means that the star as seen by the naked eye will be quite some distance from where it really is. Students of trigonometry will understand; a second of arc will subtend a cosmic sine at the end of four light years. To help the pilot, the spotter was used. The spotter was a tender spacecraft that roamed the solar system far out from Sol. Two light hours away it was. When one of the star ships was scheduled to fly, the elecalc would compute the course and the big telescopes would direct the spotter spacecraft via the Z-wave until the distant ship was directly in the line of aim between Terra and the calculated spot in the heavens where the distant star would be at the end of the ship's flying time. Once the spotter was properly located, two hours before the take-off time the spotter would emit an atomic spotlight for a half hour. Two hours later the light from this immense searchlight would arrive at Terra to provide an aiming point for the space pilot. The ship could take off on this line of sight, aiming for it directly. Of course, by the time the space travelling ship reached the spot, the spotter craft would have moved aside; the light would have ceased, and the star ship was heading for deep space with nothing to impede its course.