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tion after its discovery, Dr. Olbers, a physician of Bremen, who employed his leisure in astronomical observations and researches, found another planet revolving in the same region. Instead of one large planet there were two small ones. He suggested that these might be fragments of a shattered planet, and that, if so, more would probably be found. The latter part of the conjecture proved true. Within the next three years two more of these little bodies were discovered, making four in all.

Thus the matter remained for some forty years. Then, in 1845, Hencke, a German observer, found a fifth planet. The year following a sixth was added, and then commenced the curious series of discoveries which, proceeding year by year, are now carrying the number known rapidly past five hundred.

Up to 1890 these bodies had been found by a few observers who devoted especial attention to the search, and caught the tiny stars as the hunter does game. They would lay traps, so to speak, by mapping the many small stars in some small region of the sky near the ecliptic, familiarise themselves with their arrangement, and then watch for an intruder. Whenever one appeared, it was found to be one of the group of minor planets, and the hunter put it into his bag.

Quite a succession of planet-hunters appeared, some of them little known for any other astronomical work. The most successful of these in the fifties was Gold-