The remarkable agreement of prediction and discovery roused a considerable amount of interest, though the planet actually found, and named Ceres after the patron-goddess of Sicily, seemed disappointingly small. But before very long Olbers, one of the members of the original planet-hunting society, surprised the astronomical world by the discovery of a second planet which also fulfilled the condition of Bode's law; and by the end of March, 1807, two other planets equally obedient to the required numerical standard were found, the first by Harding, the second by Olbers. Thus a system of four small planets, Ceres, Pallas, Juno, and Vesta, was found to fill that gap in the series which had originally suggested the search. To account for their existence Olbers proposed the theory that they were the fragments of a large planet which had been blown to pieces either by the disruptive action of internal forces or by collision with a comet; and this theory remained in favour for a number of years, though accumulating evidence against it has forced its abandonment. It was not till 1845 that there was any addition to the number of the asteroids, as they had come to be named. In that year, however, Hencke of Driessen in Prussia, discovered a fifth, which has been named Astræa, and in 1847 repeated his success by the discovery of a sixth, Hebe. Since that time there has been a steady flow of discoveries, until at the present time the number known to exist is close upon 700, of which 569 have received permanent numbers as undoubtedly distinct members of the solar system; and this total is being steadily added to year by year, the average annual number of discoveries for the years 1902 to 1905 inclusive, being fifty-two. For a time the search for minor planets was a most laborious business. The planet-hunter had to construct careful maps of all the stars visible in a certain small zone of the ecliptic, and to compare these methodically with the actual face of the sky in the same zone, as revealed by his telescope. Any star seen in the telescope, and not found to be marked upon the chart, became forthwith an object of grave suspicion, and was watched until its motion, or lack of motion, relatively to the other stars either proved or disproved its planetary nature. At present this lengthy and wearisome process has been entirely superseded by the photographic method, in which a minor planet is detected by the fact that, being in motion relatively to the fixed stars, its image will appear upon the plate in the shape of a short line or trail, the images of the fixed stars being round dots. Of course the trail may be due to a planet which has already been discovered; but should there be no known minor planet in the position occupied by the trail, then a new member has been added to the system. Minor-planet hunting has always been a highly specialized branch of astronomy, and a few observers, such as Peters, Watson, Charlois and Palisa, and at present