# Dictionary of National Biography, 1927 supplement/Strutt, John William

​STRUTT, JOHN WILLIAM, third Baron Rayleigh (1842–1919), mathematician and physicist, was born at Langford Grove, Maldon, Essex, 12 November 1842, the eldest son of John James Strutt, second baron, by his marriage with Clara Elizabeth La Touche, eldest daughter of Captain Richard Vicars, R.E., and sister of Hedley Shafto Johnstone Vicars [q.v.]. As is said to have been the case with so many men of exceptional talent, he was a seven months' child. Throughout his infancy and youth he was of frail physique; his education was repeatedly interrupted by ill-health, and his prospects of attaining maturity appeared precarious. He entered Eton at the age of ten, but stayed only one half, a large part of which was spent in the school sanatorium. After three years at a private school at Wimbledon he went to Harrow, where his stay was almost as short as at Eton. In the autumn of 1857 he was put under the care of the Rev. George Townsend Warner, who took pupils at Torquay. Here he remained for four years, the surroundings proving more congenial and his health better than at his former schools. Having competed unsuccessfully for a scholarship at Trinity College, Cambridge, in 1860, he entered the college as a fellow-commoner in October 1861, and at once commenced reading for the mathematical tripos under Dr. E. J. Routh [q.v.], of Peterhouse. Although he was ‘coached’ privately during the summer he was not at first equal in mathematical attainments to the best of his contemporaries. But his exceptional abilities soon enabled him to overtake all his competitors, and it caused no surprise that the senior wranglership fell to him in January 1865. There still lingers in Cambridge a tradition as to the lucidity and literary finish of his answers in this examination. One examiner is said to have averred that they could have been printed without revision, and another that ‘Strutt's answers were better than the books’. The fine sense of literary style which he displayed in the press of examinations never deserted him; every paper he wrote, even on the most abstruse subject, is a model of clearness and simplicity of diction, and conveys the impression of having been written without effort.
As a boy, Strutt had shown a distinct interest, although perhaps nothing more, in experimental science; his pocket money was spent on sulphuric acid, magnets, and an electric machine, while both in school and undergraduate days he took a great interest in the then infant science of photography. Four months before the tripos examination he had been awarded the Sheepshanks exhibition in astronomy, but astronomy at this time offered little to attract a powerful mind, and it was his earlier tastes and interests that determined his choice of occupation after he had taken his degree. He began by taking a course of chemical analysis with G. D. Liveing, the newly-appointed professor of chemistry. The choice of subject may seem strange, but the only experimental courses then available were those in chemistry, mineralogy, and certain biological sciences, a narrowness of choice which Strutt greatly resented. ‘It wasted three or four years of my life’, he said in later years. From now on his academic career was that normal to a man of his intellectual attainments. The first Smith's prize fell to him in 1865, he was elected a fellow of his college in the next year, and a fellow of the Royal Society in 1873.
In 1871 he married Evelyn, daughter of James Maitland Balfour, of Whittingehame, East Lothian, and sister of Mr. Arthur (afterwards Earl of) Balfour, the future prime minister. This step involved the resignation of his fellowship at Trinity and resulted in a temporary severance of his connexion with Cambridge. The year after his marriage, a severe attack of rheumatic fever led to his devoting a winter to travel in Egypt and Greece. Shortly after his return his father died (June 1873), and he succeeded as third Baron Rayleigh, taking up his residence in the family seat, Terling Place, Witham, Essex. Although, as throughout his life, his primary interest was scientific research, he now found himself compelled to devote a part of his time to the management of his estates, which were somewhat embarrassed by the prevailing agricultural depression. He acquired, or perhaps rather had forced upon him, a considerable knowledge of agriculture, which, combined with his general scientific knowledge and acumen, led to his practice in estate management being in many respects in advance of the time. He was especially interested in experimenting with artificial ​fertilisers, and was a pioneer in the use of nitrate of soda. After 1876 he left the entire management of the land to his younger brother, Edward Strutt.
This period saw the commencement of Rayleigh's lifelong interest in psychical research. At first he expected that investigation would rapidly lead to a definite conclusion, either positive or negative. Apparently he expected the former, in which case, his son believes, he was prepared to throw the greater part of his energies into a study of psychic phenomena. When it became clear that no such definite conclusion was being attained, he returned to orthodox scientific work. His recreations at this time were travel, tennis, and photography; a taste for music he shared with his wife. Shooting parties, which for some years he gave every winter, and ordinary social engagements, occupied but a small part of his time; it was not until later years that Terling became a gathering place for scientists from all the corners of the earth. He held strong conservative, and still stronger unionist, opinions, but the possibility of a political career did not attract him. He seconded the address in the House of Lords in 1875, and on rare occasions intervened in debate, but in general was resolute in not allowing politics to interfere with science.
Although he had taken his degree in 1865, and had immediately afterwards embarked on the experimental study of chemistry, it was not until 1869 that Rayleigh's first scientific paper appeared, bearing the title Some Electro-magnetic Phenomena considered in connexion with the Dynamical Theory. The paper has an interest beyond that which generally attaches to the first efforts of even the most brilliant investigators, in that it was a perfect example of the method its author was to pursue throughout his career. A dynamical theory of the electro-magnetic field had been given by James Clerk-Maxwell [q.v.] in terms of abstruse mathematical equations. Rayleigh elucidated and simplified this recondite theory—almost, one might say, made it intelligible to the average man—by showing that the intricate processes of the electro-magnetic field found practically perfect analogies in such well-understood phenomena as the bursting of a water-pipe under sudden pressure and the action of a hydraulic ram. The capacity for understanding everything just a little more deeply than anyone else, and the consequent capacity for exhibiting it in its simplest aspect, which formed so marked a characteristic of all Rayleigh's writings, was fully apparent in this, his first paper, which, as Sir Arthur Schuster remarks, ‘bears the imprint of the craftsman marked as clearly as a picture by Perugino carries the signature of the artist in every square inch’. From now until his death the 446 papers which are reprinted in the six volumes of his collected works issued in a steady, unbroken flow. Except for a period of intense activity while he held the Cavendish professorship at Cambridge, these papers appeared with remarkable regularity at the rate of about nine a year. Each records some definite clear-cut advance, and records it in a perfectly direct and unambiguous manner. Limitations of space prevent reference to more than the outstanding landmarks of his scientific life.
In the period between his first paper (1869) and his election to the Cavendish professorship (1879), Rayleigh's work dealt mainly with electrical questions, problems of light and colour, and dynamical questions of resonance and vibrations both of gases and of elastic solids. His investigations in these latter subjects ultimately formed the foundation of his Treatise on the Theory of Sound. This, the only textbook he ever wrote, was begun during his Egyptian tour in 1873, but was not published until 1877, when it at once took rank as the leading book on the subject, a position it has retained ever since.
In 1879 Clerk-Maxwell died, after holding for only eight years the Cavendish professorship of experimental physics which had been founded for him at Cambridge. In accordance with a widely-expressed wish, the professorship was re-established specially for Lord Rayleigh, and he was duly elected in December 1879. The taking up of his professorial duties not only marks the commencement of the most active period of his scientific life, but coincides also with a change in the nature of his papers. He thought it important that the energies of the laboratory under his charge should be devoted in the main to some one big problem of research in which all who wished could take part. The subject selected was a re-determination of the electrical units in absolute measure. Measurements had been made by a committee of the British Association in 1863, but doubt had been thrown on their accuracy, and a re-determination was urgently needed. The subject had the disadvantage of giving but little scope to the originality or intellectual powers of an ambitious student, but Rayleigh succeeded in persuading a band of workers, some of whom have since risen ​to the highest scientific positions, to buckle down to the tedious drudgery involved in exact measurements. The result was the classical series of papers published, mainly by the Royal Society, in 1881–1883, and reprinted in volume ii of Rayleigh's collected works.
Finding his life at Cambridge rather too exacting, Rayleigh resigned his professorship at the end of 1884 and retired to Terling to pursue his researches in his private laboratory. A few months later he accepted the secretaryship of the Royal Society, vacant through the resignation of Sir George G. Stokes. The duties of this office were not so onerous as they have since become, but that he found them sufficiently so is suggested by a sentence which he wrote in the obituary notice of his predecessor. Commenting on the marked decrease of scientific output resulting from Stokes's acceptance of the secretaryship, he remarked, ‘The reflexion suggests itself that scientific men should be left to scientific work and should not be tempted to assume heavy administrative duties, at any rate until such time as they have delivered their more important messages to the world’. No such falling-off occurred in Rayleigh's work, his output of work being consistently high throughout his eleven years of secretaryship. The tenure of this office gave him the opportunity to discover and rescue from oblivion the valuable memoir in which J. J. Waterston in 1846 had anticipated some of the important features of the kinetic theory of gases. During this period he began his experimental determinations of the densities of gases, of which the culminating success was the discovery of argon in 1894. In 1892 he had announced that two samples of nitrogen which he had prepared in chemically different ways had shown densities differing by as much as one part in 1,000, and had concluded that such a difference could be attributed only to a variation in the character of the gas. Gradually he was led to the view that what had so far been regarded as pure atmospheric nitrogen was a mixture of chemical nitrogen and some heavier atmospheric constituent. Sir William Ramsay [q.v.] joined the research in its later stages, the final outcome being the classical paper Argon, a new Constituent of the Atmosphere which was communicated to the Royal Society by Rayleigh and Ramsay jointly on 31 January 1895. About this time Rayleigh became deeply interested in physical optics. His researches in this subject will perhaps constitute his most enduring title to fame, the papers in which they are recorded, over 150 in number, are probably those in which his intellectual powers are displayed to best advantage, and he himself said, when late in life he thanked the Royal Society for the award of their Rumford medal, that they were those which had given the greatest pleasure to their author.
In his later years honours and responsibilities fell thick upon Rayleigh. He was one of the original recipients of the order of merit in 1902; he received a Nobel prize, jointly with Sir William Ramsay, in 1904, and he was made a privy councillor in 1905. In the same year he was elected president of the Royal Society, and in 1908 succeeded the Duke of Devonshire as chancellor of the university of Cambridge. Some of the most arduous, although probably also most pleasant, duties of his later life centred in his association with the National Physical Laboratory. He acted as chairman of the Treasury committee which reported in favour of its formation in 1898, and presided with unfailing regularity over the meetings of its executive committee until the onset of his last illness. In 1909 he was appointed president of the special government advisory committee on aeronautics, an appointment which led to his taking great interest in, and devoting much time to, problems of aviation.
The passing of Lord Kelvin left Rayleigh undisputed leader of British science on the physical side. It is no easy task to explain to the layman the grounds on which this supremacy was unanimously accorded him. His massive, precise, and perfectly balanced mind was utterly removed from that of the erratic genius who typifies the great scientist in the popular imagination. Of striking discoveries or inventions practically none stand to his credit with the single exception of the discovery of argon. His special aptitude was for arranging and levelling up existing knowledge rather than for taking giant strides into unexplored country. The outstanding qualities of his writings were thoroughness and clearness: he made everything seem obvious. These talents which would have been dangerous in a man of less sound judgement, or one less scrupulously careful not to lead others astray, were safe in Rayleigh's keeping. The inscription on his memorial in Westminster Abbey, ‘An unerring leader in the advancement of natural knowledge’, does not overstate the case. His researches covered almost the whole field of exact ​science; he was apparently equally at home in physics, chemistry, and mathematics. Although professing but little patience with the refinements of modern pure mathematics, he could always muster the technique necessary for the treatment of a practical problem, and his solutions, invariably direct, artistic, and workmanlike, never fail to inspire admiration for his mastery of mathematical methods. Although not directly concerned with the great strides made by molecular physics in the latter years of his life, his judgement in these matters, in strong contrast with that of some of his contemporaries, was always fair, open-minded, and acute. His record of scientific work, great though it is, would have been greater had it not been that he felt it a duty to shoulder any administrative responsibility under which he believed that he could achieve valuable work. His personal preference would have undoubtedly been for pursuing his scientific investigations in the quiet of his country seat and the detachment of his private laboratory.
Rayleigh died at Witham, Essex, on 30 June 1919, having been at work on a scientific paper only five days previously. Although his physical health had for some time been feeble his mind had retained its power to the end. By his marriage he had three sons, of whom the eldest, Robert John Strutt (born 1875), already well known as a physicist, succeeded to the barony.
A portrait of Lord Rayleigh in his robes as chancellor of the university, painted by Sir Hubert von Herkomer in 1911, hangs in the Examination Hall at Cambridge; another portrait, by Sir George Reid, is in the rooms of the Royal Society (Royal Academy Pictures, 1911).
[Robert John Strutt, fourth Baron Rayleigh, John William Strutt, third Baron Rayleigh, 1924; Proceedings of the Royal Society, vol. xcviii, A, 1921 (with portrait); Sir R. T. Glazebrook, The Rayleigh Period, in The History of the Cavendish Laboratory, 1910; personal knowledge.]
J. H. J.