from the à priori method depending on laws of attraction, which was inherited from the astronomers ; for this there was substituted a combination of the powerful analysis by partial differentials, already cultivated by Laplace and Fourier, with close attention to the improvement of physical ideas and modes of expression of natural phenomena. The way was thereby prepared for Clerk Maxwell's interpretation of Faraday, and for the modern wide expansion of ideas.
The copious early output of Stokes's own original investigation slackened towards middle life. In 1851 he had been elected F.R.S., and next year was awarded the Rumford medal for his discovery of the nature of fluorescence. In 1854 he became secretary of the Royal Society, and the thirty-one years of his tenure of this office (1854-5) were devoted largely to the advancement of science in England and the improvement of the publications of the Royal Society. There were few of the memoirs on physical science that passed to press through his hands that did not include valuable extensions and improvements arising from his suggestions. When the Indian geodetic survey was established, he was for many years its informal but laborious scientific adviser and guide. The observatory for solar physics, which was founded in 1878, was indebted to him in a similar manner. His scientific initiative as a member of the meteorological council, who managed from J1871 the British weather service, was a dominant feature of their activity. During these years the imperfect endowment of his chair at Cambridge made it necessary for him to supplement his income from other sources : thus he was for some time lecturer at the School of Mines, and a secretary of the Cambridge University Commission of 1877-81. He had vacated his fellowship at Pembroke on his marriage in 1857, but was re-elected under a new statute in 1869.
In 1883 Stokes was appointed, under a new scheme, Burnett lecturer at Aberdeen, and delivered three courses of lectures on 'Light' (1883-5), which were published in three small volumes (1884-7). In 1891 he became Gifford lecturer at Edinburgh, and delivered other three courses on the same general subject (1891-3). The theme in all these courses was treated from the point of view of natural theology, as the terms of the foundations required. His interests as a churchman and theologian were strong through life, and found occasional expression in print. He often took part in the proceedings of the Victoria Institute in London, which was founded for inquiry into Christian evidences. Stokes received in his later years nearly all the honours that are open to men of science. He was president of the British Association at the Exeter meeting in 1869. In 1885 he succeeded Professor Huxley as president of the Royal Society, holding the office till 1890, when he was himself succeeded by his friend Lord Kelvin ; he remained on the council as vice-president two years longer, and on his retirement he was immediately awarded in 1893 the society's Copley medal. On the death of Beresford-Hope in 1887, he was elected without opposition, in the conservative interest, one of the members of parliament for Cambridge University, and he sat in the House of Commons till 1891. He was a royal commissioner for the reform of the University of London (1888-9). In 1889 he was created a baronet (6 July). In 1899 the jubilee of his tenure of the Lucasian chair was celebrated at Cambridge by a notable international assembly. Through the friendship of Hofmann, Hehnholtz, Comu, Becquerel, and other distinguished men, he became in his later years widely known abroad ; and the Prussian order pour le mérite and the foreign associateship of the Institute of France were conferred on him. At his jubilee celebration the Institute of France sent him the special Arago medal ; and he was one of the early recipients of the Hehnholtz medal from Berlin. He received honorary doctor's degrees from Edinburgh, Dublin, Glasgow, and Aberdeen, as well as from Oxford and Cambridge. In October 1902 his colleagues of Pembroke College, of which he had long been fellow and of late years president, elected him Master. He died at Cambridge on 1 Feb. 1903, and was buried there at the Mill Road cemetery.
Stokes married on 4 July 1857 Mary (d. 30 Dec. 1899), daughter of Thomas Romney Robinson, the astronomer [q. v.], and left issue two sons and one daughter. His elder son, Arthur Romney Stokes succeeded him as second baronet.
Stokes's writings have been collected into five volumes of 'Mathematical and Physical Papers' (Cambridge, 1880-1905) of which the first three were carefully edited by himself, and the other two were prepared posthumously by Sir Joseph Larmor, his successor in the Lucasian chair. Two volumes of his very important 'Scientific Correspondence' were published in 1907 under the same editorship, and
