Messier, viewing the planet in 1766 with what he calls "an achromatic reflector of 10 feet 7 inches focus," "perceived on his globe two darkish belts, extremely faint and difficult to be discerned, directed, however, in a right line parallel to the longest diameter of the ring."[1] However, till Herschel applied his 40-feet reflector to its system, discovery may be said to have reached its limits. To "the liberal support, whereby our most benevolent King has enabled his humble astronomer to complete the arduous undertaking of constructing this instrument," Herschel writes, was due the discovery of other two moons or satellites, a fuller knowledge of the nature of the ring, and, in short, a new era in our knowledge of that wonderful system. An object so engaging drew Herschel's attention as early as the spring of 1774, long before he was known to fame. On the 17th of March that year, with a 512-feet reflector, he saw the ring "reduced to a very minute line," and the planet looking like a ball with a knitting-needle projecting through it on both sides. About a fortnight after, the ends of this axis had vanished, and a dark band or shadow crossed the planet's equator from side to side. In the following year he saw the ring gradually open out, with a "dark zone contained between two concentric circles," as if there were two rings with an open space between them. For ten years he continued watching the planet with telescopes of various powers, suspicious that it had not told astronomers all the story of its ring and satellitea The ten years' watch lengthened out to twenty, and the twenty to thirty or more, but this eager watcher still kept guard, ready to take advan-
- ↑ Phil. Trans., 1769., vol. lix. p. 459.
