There lies the gist of the matter. If the change of position can be observed, well and good! The length of the base-line being known, the distance of the star may be mathematically calculated. For the size of the tiny apparent path, followed in a year by the star, is and must be exactly proportioned to the distance of the star from that base-line. If the tiny oval be so much larger, then the star is known to be so much nearer. If the tiny oval be so much smaller, then the star is known to be so much farther away. But when not the minutest token could be discovered of a star’s position in the sky being in the least degree affected by the earth’s great annual change of position, astronomers were at a loss. There was absolutely nothing to calculate from. The star was a motionless point to earth. The whole yearly orbit of earth was a motionless point to the star. One slender beam of light united the two. Reckoners had nothing to stand upon. It is interesting to know that Copernicus had actually, long before, suggested this as a possible explanation of the absence of star-parallax. He thought that astronomers might fail altogether to find it, because the stars might be “at a practically infinite distance” from our earth. CHAPTER XXVII. MEASUREMENT OF STAR DISTANCES. Until the days of Sir William Herschel, little attention was bestowed upon the universe of distant stars. Before his advent the interest of astronomers had been mainly centered in the sun and his revolving worlds. The “fixed stars” were indeed studied, as such, with a certain amount of care, and numberless efforts were made to discover their distances from earth; but the thought of a vast Starry System, in which our little Solar System should sink to a mere point by comparison with its immensity, had not yet dawned. With larger and yet larger telescopes of his own making, Herschel studied the whole Solar System, and especially the nature of sun-spots, the rings of Saturn, the various motions of attendant moons, together with countless other details. He enlarged the system by the discovery of another planet outside Saturn--the planet Uranus, till then unknown. These were only first steps. The work which he did in respect of the Solar System was as nothing compared with the work which he did among the stars. His work in our system was supplementary to other men’s labors; his work among the stars was the beginning of a new era. Like many before him, he, too, sought eagerly to find star-parallax, and he, too, failed. Not yet had instruments reached a degree of finish which should permit measuring operations of so delicate a nature.