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 himself to the advancement of that science. Such a life naturally was of a quiet tenor, and Cayley did not possess the ambition of playing a prominent part in public life. Indeed, it was seldom that duties fell to him which brought him into popular notice; perhaps the most conspicuous exception was his presidency of the British Association in 1883. Scientific honours came to him in copious measure. He was made an honorary fellow of Trinity in 1872, and three years later was made an ordinary fellow once more, his first tenure having lapsed in 1852. He received honorary degrees from many bodies, among others from Oxford, Dublin, Edinburgh, Gottingen, Heidelberg, Leyden, and Bologna, as well as from his own university. From the Royal Society of London (of which he was elected fellow on 3 June 1852) he received a Royal medal in 1859 and the Copley medal in 1882, the latter being the highest honour which that body can bestow. In addition to membership of all the leading scientific societies of his own country, he was an honorary foreign member of the French Institute and of the academies of Berlin, Gottingen, St. Petersburg, Milan, Rome, Leyden, Upsala, and Hungary; and he accepted an invitation from the Johns Hopkins University, Baltimore, to deliver a special course of lectures there, discharging this office between December 1881 and June 1882. His life pursued an even scientific course, and his productive activity in mathematics was terminated only by his death, which occurred at Cambridge on 26 Jan. 1895. He is buried in the Mill Road cemetery, Cambridge. His portrait, painted by Mr. Lowes Dickinson in 1874, hangs in the dining hall of Trinity college; and a bust, by Mr. Henry Wiles, was placed in 1888 in the library of that college.

Cayley contributed to nearly every subject in the range of pure mathematics, and some of its branches owe their origin to him. Conspicuously among these may be cited the theory of invariants and covariants; the general establishment of hypergeometry on broad foundations, and specially the introduction of 'the absolute' into the discussion of metrical properties; the profound development of branches of algebra, which first were explained in a memoir on matrices; contributions to the theory of groups of operations; and advances in the theory of the solution of the quintic equation. Not less important were his contributions to the theory of analytical geometry, alike in regard to curves and to surfaces. There is hardly an important question in the whole range of either subject in the solution of which he has not had some share. Nor is it to the various theories in pure mathematics alone that he contributed. His services in the region of theoretical astronomy were of substantial importance; and in one instance he was enabled, by an elaborate piece of refined analysis, to take part in settling a controversy between his friend, John Couch Adams [q. v. Suppl.], and some French astronomers. Also, in framing any estimate of his work, account should be taken of the various papers he wrote upon theoretical dynamics, and in particular of two reports upon that subject presented to the British Association. It remains, of course, with the future to assign him his position among the masters of his science. By his contemporaries he was acknowledged one of the greatest mathematicians of his time.

As regards his publications, the body is to be found in the memoirs contributed, through more than fifty years, to various mathematical journals and to the proceedings of learned societies. His papers, amounting to more than nine hundred in number, have been collected and issued in a set of thirteen volumes, together with an index volume, by the Cambridge University Press (1889-98). Cayley himself published only one separate book, 'A Treatise on Elliptic Functions' (Cambridge, 1876; a second edition, with only slight changes, was published in 1895 after his death).  CECIL, ARTHUR, whose real name was (1843–1896), actor, born near London in 1843, played as an amateur at the Richmond theatre and elsewhere, and made, as Arthur Cecil, on Easter Monday 1869, his first professional appearance at the Gallery of Illustration with the German Reeds as Mr. Churchmouse in Mr. Gilbert's 'No Cards,' and Box in the musical rendering of 'Box and Cox' by Mr. Burnand and Sir Arthur Sullivan. In 1874 he joined the company at the Globe, appearing on 24 Jan. as Jonathan Wagstaff in Mr. Gilbert's 'Committed for Trial,' and playing on 6 April Mr. Justice Jones in Albery's 'Wig and Gown.' At the Gaiety on 19 Dec. he was Dr. Caius, and in the following February, at the Opera Comique, Touchstone. Other parts in which he was seen were Sir 