1850-60] ROYAL ASTRONOMICAL SOCIETY 115 does the word spectrum appear in the index to the Monthly Notices until 1863, when Airy, at the March meeting, described a spectro- scope used at Greenwich on fixed stars. The number for 1856 May had, however, contained a short " Description of an Observatory erected at Upper Tulse Hill," by William Huggins, who was then devoting himself to the study of astronomy with the intention of making it his life work. How quickly he seized the splendid promise of Kirchhoff's work, and to what fruitful use he put it, is familiar to all, but, in any case, falls outside our period and cannot be told here. The year 1850 found astronomers still greatly interested in the discovery of new minor planets ; ten of these bodies were then known, and their number was being added to yearly. In 1853 February, twenty-three were known, and by 1860 January, the total had risen to fifty-seven. While the number known was small, it was confidently expected that the end would soon be reached and the whole group named and accounted for. Thus we find the Report of the Council for the year ending 1851 February, after recording the discovery of three more, said : "A rate of increase among the known members of the solar system which can hardly be expected to continue very long." When, however, it began to be suspected that the rate of discovery was a function of the in- crease of telescopic power, that greater efficiency and higher magnification simply meant that the existence of smaller and smaller planets was disclosed and that their total number was, for all practical purposes, infinite, the interest of the search waned. Now the only justification that remains for continuing this search is the possibility of finding one with an exceptional orbit, such as was the case with Eros, where the fact that its orbit at times comes inside that of Mars makes it the most accurate gauge for the measurement of the solar parallax. In one particular direction the Astronomical Society found the rapid multiplication of these bodies a decided embarrassment. Their ephemerides had always been published in the Monthly Notices, but the bulk of this matter became too great, and in 1854 February the Editor reported that, as communications of this nature could be published with greater regularity as well as earlier and more fully in the Astronomische N achrichten, they would disappear from the Monthly Notices. The two most active observers and discoverers of these little bodies at this time were J. R. Hind, and A. de Gasparis of Naples. Both received the Gold Medal, Gasparis in 1851 and Hind in 1853. The President in the first-named year was Airy, and in his address he set forth the three known ways of detection, viz., accident, physical properties, e.g. recognition of the planet by its disc, and
