Such motions had never been carefully noted or examined, until Herschel came to do away with the old received notions of star-fixity. Happily, Herschel was no slave to “received ideas.” Like Galileo in earlier times, he wished to “prove all things” personally, anxious only to find out what was the truth. And he found that the stars were _not_ fixed! He found that numbers of them were moving. He conjectured that probably all the rest were moving also; that in place of a fixed universe of changeless stars we have a whirling universe of rushing suns. Herschel could not, of course, watch any one star for a hundred years, much less for several centuries. But in a very few years he could, by exceedingly close measurement, detect sufficient motion to be able to calculate how long it would take a certain star to creep across a space as wide as the full moon. From step to step he passed on, never weary of his toil. He sought to gauge the Milky Way, and to form some notion of its shape. He noted a general drift of stars to right and to left, which seemed to speak of a possible journey of our sun through space, with all the planets of the Solar System. He flung himself with ardor into the study of star-clusters and of nebulæ. He saw, with an almost prophetic eye, the wondrous picture of a developing universe--of nebulæ growing slowly into suns, and of suns cooling gradually into worlds--so far as to liken the heavens to a piece of ground, containing trees and plants in every separate stage of growth. And still the search for star parallax went on, so long pursued in vain. No longer base-line than that of the diameter of earth’s yearly orbit lay within man’s reach. But again and yet again the attempt was made. Instruments were improved, and measurements became ever more delicate; and at length some small success crowned these persistent endeavors. The tiny sounding-line of earth, lowered so often into the mysterious depths of space, did at last “touch bottom.” Herschel died, full of years and honors, in 1822; and some ten years later three different attempts proved, all to some extent, and almost at the same date, successful. Bessel, however, was actually the first in point of time; and his attempt was upon the double-star, 61 Cygni; not at all a bright star, but only just visible to the naked eye. There are stars and stars, enough to choose from. The difficulty always was, which to select as a subject for trial with any reasonable prospect of a good result. Some astronomers held that the brightest stars were the most hopeful, since they were probably the nearest; and of course the nearer stars would show parallax more readily, because their parallax would be the greater. But certain very bright stars indeed are now known to be far more distant than certain very dim stars.