sidereal astronomy. Although struck with the comparative paucity of close double stars, he discovered and measured 1,202 pairs; 1,708 nebulæ and clusters, 1,269 of them previously unseen, figured in his lists; his chart of the Argo nebula gave the places of 1,203 stars; he catalogued 1,163 objects in both Magellanic Clouds; ‘monographed’ the Orion and other great nebulæ; and determined micrometrically the components of the ‘jewelled’ cluster in Crux. ‘Gauging’ the skies on his father's principle, he concluded the Milky Way, from a count of some 69,000 stars in 2,299 fields, to be an annulus rather than a disc of stars. He set the example of employing an ‘artificial star’ in stellar photometry, and skilfully applied the ‘method of sequences’ to fix the relative lustre of nearly five hundred stars, thereby laying a sure foundation for stellar magnitudes. The object aimed at was to range all the lucid stars along a single scale of brightness; and in order to link together southern and northern skies, the work of estimation was carried on on board ship in varying latitudes. Several specimens of the actinometer (described in 1825 in Edinb. Journ. of Science, iii. 107), with which at the close of 1836 he made the first satisfactory measures of direct solar radiation, were shown at the Meteorological Society's exhibition of instruments in 1889. The numerous sun-spots of 1836–7 engaged his close attention, and he suggested, in a letter to Baily of 1 March 1837, the now established relation between solar and auroral activity. His observations of Halley's comet between 28 Oct. 1835 and 5 May 1836 (Memoirs Roy. Astr. Soc. x. 325) gave strong support to the theory of electrical repulsion. From a series of observations of Saturn's satellites he derived corrected elements for those bodies, and the first independent confirmation of his father's discovery of the two next the ring. These multiplied labours were accomplished with only the aid of a mechanic named John Stone; but they were lightened by the cordial sympathy of Sir Thomas Maclear [q. v.], then H.M. astronomer at the Cape.
The public interest in this expedition was shown by the grotesque announcements of lunar discoveries at Feldhausen, made satirically by R. A. Locke in the ‘New York Sun’ for September 1835 (The Moon Story, New York, 1852). The excellent system of national education prevailing in the colony was initiated by Herschel, and he set on foot a plan of simultaneous meteorological observations, developed in his ‘Instructions for Making and Registering Meteorological Observations at various Stations in South Africa,’ printed in 1838 among the ‘Professional Papers of the Royal Engineers’ (ii. 214). Numerous tidal observations were sent by him to Dr. Whewell from the Cape. A few days before his departure from the Cape the members of the South African Literary and Scientific Institution, over which he had presided, presented him with a gold medal; and on 15 Feb. 1842 an obelisk of Craigleath stone was erected on the site of his great reflector.
Herschel's observation, on 16 Dec. 1837, of the sudden rise of the star η Argûs from the second to the first magnitude (Monthly Notices, iv. 121; Cape Results, p. 32) constituted him the virtual discoverer of its abnormal character. He sailed in the Windsor Castle in the middle of March 1838, and landed in England after nine weeks, in part occupied by the continuance of his photometric estimates. A baronetcy (reluctantly accepted) was conferred upon him at the queen's coronation; he was created D.C.L. of the university of Oxford on 12 June 1839. He declined to enter parliament as the representative of the sister university, and refused a proposal that he should succeed the Duke of Sussex as president of the Royal Society, but was elected in 1842 lord rector of Marischal College, Aberdeen, and acted as president of the British Association at Cambridge in 1845. Almost every learned society in Europe and several in America placed his name on their lists of members; he was made chevalier of the Prussian order ‘Pour le Mérite,’ and on 23 July 1855 was chosen, on the decease of Gauss, one of the eight foreign associates of the French Institute.
He paid his last visit to Miss Herschel at Hanover in July 1838, dining with Olbers at Bremen on his return, and attending the meeting of the British Association at Newcastle in August. He was here appointed a member of a committee for reducing Lacaille's stars, and wrote the preface to the catalogue of them published in 1847. The promotion of a scheme, then recently started by Humboldt and Gauss, for widespread magnetic observations mainly devolved upon him; he drew up a memorial to government on the subject, composed the instructions for Sir James Ross's southern expedition, and reported progress year after year at successive meetings of the British Association. Still more laborious was the task, first attacked at the Cape, of revising the nomenclature of southern stars. He prepared charts (presented to the Royal Astronomical Society in 1867, Monthly Notices, xxvii. 213, xxviii. 92) of all the lucid stars in both hemispheres, assigning the brightness of each within a third of a magnitude; communicated a large project of constellational reform to the Royal Astro-
