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STOKES, SIR GEORGE GABRIEL, BART

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Originally appearing in Volume V25, Page 953 of the 1911 Encyclopedia Britannica.
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STOKES, See also:SIR See also:GEORGE See also:GABRIEL, See also:BART . (1819—1903), See also:British mathematician and physicist, was the youngest son of the Rev. Gabriel Stokes, See also:rector of Skreen, Co. See also:Sligo, where he was See also:born on the 13th of See also:August 1819. After attending See also:schools in See also:Dublin and See also:Bristol, he matriculated in 1837 at See also:Pembroke See also:College, See also:Cambridge, where, four years later, on graduating as See also:senior wrangler and first See also:Smith's prizeman, he was elected to a fellowship. This he had to vacate by the statutes of that society when he married in 1857, but twelve years later, under new statutes, he was re-elected, and retained his See also:place on the See also:foundation until 1902, when, on the See also:day before he entered on his eighty-See also:fourth See also:year, he was elected to the mastership. But he did not See also:long enjoy this position, for he died at Cambridge on the 1st of See also:February in the following year. In 1849 he was appointed to the Lucasian professorship of See also:mathematics in the university, and on the 1st of See also:June 1899 the See also:jubilee of his See also:appointment was celebrated at Cambridge in a brilliant ceremonial, which was attended by numerous delegates from See also:European and See also:American See also:universities. On that occasion a commemorative See also:gold See also:medal was presented to him by the See also:chancellor of the university, and See also:marble busts of him by Hamo See also:Thornycroft were formally offered to Pembroke College and to the university by See also:Lord See also:Kelvin. Sir George Stokes, who was created a See also:baronet in 1889, further served his university by representing it in See also:parliament from 1887 to 1892. During a portion of this See also:period (1885—189o) he was See also:president of the Royal Society, of which he had been one of the secretaries since 1854, and thus, being at the same See also:time Lucasian See also:professor, he See also:united in himself three offices which had only once before been held by one See also:man, Sir See also:Isaac See also:Newton, who, however, did not hold all three simultaneously. Stokes was the See also:oldest of the t>'io Q£ natural philosophers, Clerk See also:Maxwell and Lord Kelvin being the other two, who especially contributed to the fame of the Cambridge school of mathematical physics in the See also:middle of the 19th See also:century.

His See also:

original See also:work began about 184o, and from that date onwards the See also:great extent of his output was only less remarkable than the brilliance of its quality. The Royal Society's See also:catalogue of scientific papers gives the titles of over a See also:hundred See also:memoirs by him published down to 1883. Some of these are only brief notes, others are See also:short controversial or corrective statements, but many are really long and elaborate See also:treatises. In See also:matter his work is distinguished by a certain definiteness and finality, and even of problems, which when he attacked them were scarcely thought amenable to mathematical See also:analysis, he has in many cases given solutions which once and for all See also:settle the See also:main principles. This result must be ascribed to his extraordinary See also:combination of mathematical See also:power with experimental skill, for with him, from the time when about 184o he fitted up some See also:simple See also:physical apparatus in his rooms in Pembroke College, mathematics and experiment ever went See also:hand in hand, aiding and checking each other. In See also:scope his work covered a wide range of physical inquiry, but, as See also:Alfred See also:Cornu remarked in his Rede lecture of 1899, the greater See also:part of it was concerned with waves and the transformations imposed on them during their passage through various See also:media. His first published papers, which appeared in 1842 and 1843, were on the steady See also:motion of incompressible fluids and some cases of fluid motion; these were followed in 1845 by one on the See also:friction of fluids in motion and the See also:equilibrium and motion of elastic solids, and in 185o by another on the effects of the See also:internal friction of fluids on the motion of pendulums. To the theory of See also:sound he made several contributions, including a discussion of the effect of See also:wind on the intensity of sound and an explanation of how the intensity is influenced by the nature of the See also:gas in which the sound is produced. These inquiries together put the See also:science of hydro-See also:dynamics on a new footing, and provided a See also:key not only to the explanation of many natural phenomena, such as the suspension of clouds in See also:air, and the subsidence of ripples and waves in See also:water, but also to the See also:solution of See also:practical problems, such as the flow of water in See also:rivers and channels, and the skin resistance of See also:ships. But perhaps his best-known researches are those which See also:deal with the undulatory theory of See also:light. His See also:optical work began at an See also:early period in his scientific career. His first papers on the See also:aberration of light appeared in 1845 and 1846, and were followed in 1848 by one on the theory of certain bands seen in the spectrum.

In 1849 he published a long See also:

paper on the dynamical theory of diffraction, in which he showed that the See also:plane of polarization must be perpendicular to the direction of vibration. Two years later he discussed the See also:colours of thick plates; and in 1852, in his famous paper on the See also:change of refrangibility of light, he described the phenomenon of See also:fluorescence, as exhibited by fluorspar and See also:uranium See also:glass, materials which he viewed as having the power to convert invisible ultra-See also:violet rays into rays of See also:lower periods which are visible. A See also:mechanical See also:model, illustrating the dynamical principle of Stokes's explanation was shown in 1883, during a lecture at the Royal Institution, by Lord Kelvin, who said he had heard an See also:account of it from Stokes many years before, and had repeatedly but vainly begged him to publish it. In the same year, 1852, there appeared the paper on the See also:composition and See also:resolution of streams of polarized light from different See also:sources, and in 1853 an investigation of the metallic reflection exhibited by certain non-metallic substances. About 186o he was engaged in an inquiry on the intensity of light reflected from, or transmitted through, a See also:pile of plates; and in 1862 he prepared for the British Association a valuable See also:report on See also:double See also:refraction, which marks a period in the See also:history of the subject in See also:England. A paper on the long spectrum of the electric light bears the same date, and was followed by an inquiry into the absorption spectrum of See also:blood. The discrimination of organic bodies by their optical properties was treated in 1864; and later, in See also:conjunction with the Rev. W. See also:Vernon See also:Harcourt, he investigated the relation between the chemical constitution and the optical properties of various glasses, with reference to the conditions of trans- parency and the improvement of achromatic telescopes. A still later paper connected with the construction of optical See also:instruments discussed the theoretical limits to the See also:aperture of microscopical objectives. In other departments of physics may be mentioned his paper on the See also:conduction of See also:heat in crystals (1851) and his inquiries in connexion with the See also:radiometer; his explanation of the light border frequently noticed in photographs just outside the outline of a dark See also:body seen against the See also:sky (1883); and, still later, his theory of the RSntgen rays, which he suggested might be transverse waves travelling as innumerable solitary waves, not in See also:regular trains. Two long papers published in 184q —one on attractions and Clairaut's theorem, and the other on the variation of gravity at the See also:surface of the See also:earth—also demand See also:notice, as do his mathematical memoirs on the See also:critical values of the sums of periodic See also:series (1847) and on the numerical calculation of a class of definite integrals and See also:infinite series (185o) and his discussion of a See also:differential See also:equation See also:relating to the breaking of railway See also:bridges (1849).

But large as is the See also:

tale of Stokes's published work, it by no means represents the whole of his services in the See also:advancement of science. Many of his discoveries were not published, or at least were only touched upon in the course of his oral lectures. An excellent instance is afforded by his work in the theory of spectrum analysis. In his presidential address to the British Association in 1871, Lord Kelvin (Sir See also:William See also:Thomson, as he was then) stated his belief that the application of the prismatic analysis of light to See also:solar and stellar See also:chemistry had never been suggested directly or indirectly by any other savant when Stokes taught it to him in Cambridge some time See also:prior to the summer of 1852, and he set forth the conclusions, theoretical and practical, which he learnt from Stokes at that time, and which he afterwards gave regularly in his public lectures at See also:Glasgow. These statements, containing as they do the physical basis on which spectrum analysis rests, and the mode in which it is applicable to the See also:identification of substances existing in the See also:sun and stars, make it appear that Stokes anticipated See also:Kirchhoff by at least seven or eight years. Stokes, however, in a See also:letter published some years after the delivery of this address, stated that he had failed to take one essential step in the See also:argument (not perceiving that emission of light of definite refrangibility not merely permitted, but necessitated, absorption of light of the same refrangibility), and modestly disclaimed " any part of Kirchhoff's admirable See also:discovery," adding that he See also:felt some of his See also:friends had been over-zealous in his cause. It must be said, however, that See also:English men of science have not accepted this See also:disclaimer in all its fullness, and still attribute to Stokes the See also:credit of having first enunciated the fundamental principles of spectrum analysis: In another way, too, Stokes did much for the progress of mathematical physics. Soon after he was elected to the Lucasian See also:chair he announced that he regarded it as part of his professional duties to help any member of the university in difficulties he might encounter in his mathematical studies, and the assistance. rendered was so real that pupils were glad to consult him, een after they had become colleagues, on mathematical and physical problems in which they found themselves at a loss. Then during the See also:thirty years he acted as secretary of the Royal Society he exercised an enormous if inconspicuous See also:influence on the advancement of mathematical and physical science, not only directly by his own investigations, but indirectly by suggesting problems for inquiry and inciting men to attack them, and by his readiness to give encouragement and help. Several of the honours enjoyed by Sir George Stokes have already been enumerated. In addition, it may be mentioned that from the Royal Society, of which he became a See also:fellow in 1851, he received the See also:Rumford medal in 1852 in recognition of his inquiries into the refrangibility of light, and later, in 1893, the See also:Copley medal. In 1869 he presided over the See also:Exeter See also:meeting of the British Association.

From 1883 to 1885 he was See also:

Burnett lecturer at See also:Aberdeen, his lectures on Light, which were published in 1884-1887, dealing with its nature, its use as a means of investigation, and its beneficial effects. In 1891, as See also:Gifford lecturer, he published a See also:volume on Natural See also:Theology. His academical distinctions included honorary degrees from many universities, together with membership of the Prussian See also:Order Pour le Write. Sir George Stokes's mathematical and physical papers were published in a collected See also:form in five volumes; the first three (See also:Cam-See also:bridge, 188o, 1883, and 1901) under his own editorship, and the two last (Cambridge, 1904 and 1905) under that of Sir See also:Joseph Larmor, who also selected and arranged the Memoir and Scientific See also:Correspondence of Stokes published at Cambridge in 1907.

End of Article: STOKES, SIR GEORGE GABRIEL, BART

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