+---------------------------------------+ |Number| Name. | Discoverer. | Date.| |---------------------------------------| | 1 | Ceres | Piazzi | 1801 | | 2 | Pallas | Olbers | 1802 | | 3 | Juno | Harding | 1804 | | 4 | Vesta | Olbers | 1807 | |------|-----------|-------------|------| | 5 | Astraea | Hencke | 1845 | | 6 | Hebe | Hencke | 1847 | | 7 | Iris | Hind | 1847 | | 8 | Flora | Hind | 1847 | | 9 | Metis | Graham | 1848 | | 10 | Hygeia | De Gasparis | 1849 | | 11 | Parthenope| De Gasparis | 1850 | | 12 | Victoria | Hind | 1850 | | 13 | Egeria | De Gasparis | 1850 | +---------------------------------------+ [Sidenote: Hencke's long search.] Here now is a table showing how other bodies were gradually added to this first list of four, but you will see that no addition was made for a long time. Not that the search was immediately abandoned; but being rewarded by no success for some years, it was gradually dropped, and the belief gained ground that the number of the planets was at last complete. The discoverers of Uranus and of these first four minor planets all died before any further addition was made; and it was not until the end of 1845 that Astraea was found by an ex-postmaster of the Prussian town of Driessen, by name Hencke, who, in spite of the general disbelief in the existence of any more planets, set himself diligently to search for them, and toiled for fifteen long years before at length reaping his reward. Others then resumed the search; Hind, the observer of an English amateur astronomer near London, found Iris a few weeks after Hencke had been rewarded by a second discovery in 1847, and in the following year Mr. Graham at Markree in Ireland (who is still living, and has only just retired from active work at the Cambridge Observatory) found Metis; and from that time new discoveries have been added year by year, until the number of planets now known exceeds 500, and is steadily increasing. [Illustration: _By permission of Messrs. Macmillan & Co._ I.--J. C. ADAMS.] [Illustration: II.--A. GRAHAM. DISCOVERER OF THE NINTH MINOR PLANET (METIS).] [Sidenote: The photographic method.]