CHAPTER II. 15

HERSCHEL THE DISCOVERER. Solar researches—Study of Venus—Of Mars—The Asteroids—Jupiter—Saturn—Discovery of satellites—Uranian satellites—Cometary researches—Motion of the Solar System—Discovery of binary stars—Clusters and nebulæ—Nebulous stars—The Nebular Hypothesis—Star-gauging—The disc-theory—Subordinate clusters—Abandonment of the disc-theory—Second method of star-gauging—Estimate of Herschel’s work