i68 



NATURE 



[Ju: 



1919 



the more desirable as it will afford an opportunity 

 of putting on record his work as president of the 

 Advisory Committee for Aeronautics. Many of the 

 investigations of the Committee have rested on' the 

 principle of similarity, which in its application to 

 the problems of flight was first clearly explained 

 by him in one of the earlier volumes of its reports. 



For the rest, reference may be made to 

 two reviews of the volumes of " Scientific 

 Papers " which appeared in these columns for 

 July 30, 1903, and October 2^^, 1913; i" these 

 and in the article published in the series of 

 "Scientific Worthies" in Nature of August 18, 

 1904, some account of Lord Rayleigh's work is 

 given. A quotation from the first-named article 

 may perhaps be made here. After referring 

 to a paper dealing with the measurement 

 of electrical resistance, the article con- 

 tinues : "The paper exhibits in a marked 

 degree Lord Rayleigh's great capacity for seeing 

 distinctly the essential points of an experiment or 

 a measurement, and keeping that clearly in view 

 throughout. This, indeed, is the distinguishing 

 feature of his experimental work, a main factor in 

 his success. Those who knew the Cavendish 

 Laboratory when the electrical measurements were 

 going on or have since visited the laboratory at 

 Terling, from which no less important work is 

 continually being published, have sometimes been 

 surprised at the makeshift character of much of 

 the apparatus. Contrivances of wood and wire 

 and wax do duty where most men would use ap- 

 paratus elaborated with a quite unnecessary care ; 

 but in Lord Rayleigh's case, while the essential 

 instrument on which the accuracy of the result 

 really depends is as perfect as the skill of the 

 workman can make it, and, in addition, has been 

 thought out in all its details, so as to fit it best for 

 the purpose immediately in view, for the rest the 

 arrangement which comes first to hand is utilised 

 without regard to appearances. " 



The last of the great Cambridge mathematicians 

 of the past century, Cayley, Adams and Stokes, 

 Maxwell and Kelvin, Lord Rayleigh was one of 

 the famous men praised by the writer of the book 

 of Ecclesiasticus : " Leaders of the people by their 

 counsels, and by their knowledge of learning meet 

 for the people, wise and eloquent in their instruc- 

 tions. . . . Their bodies are buried in peace ; 

 but their name liveth for evermore." R. T. G. 



It is now nearly sixty years since the Hon. 

 J. W. Strutt, eldest son of the second Baron 

 Rayleigh, entered Trinity College, Cambridge, to 

 study for the Mathematical Tripos. The Lucasian 

 Professor of Mathematics, G. G. Stokes, was at 

 the time engaged in working out the laws of 

 fluorescence and in writing his report on " Double 

 Refraction" for the British Association; Prof. 

 W. Thomson, of Glasgow, had published his 

 great paper on "The Dvnamical Theorv of 

 Heat"; Prof. J. C. Maxwell, of King's College, 

 London, was writing those fundamental papers 

 on "Electrodynamics " which were incorporated 

 in his "Electricity and Magnetism "; and Balfour 

 ^'O- 2593, VOL. 103] 



Stewart, of the Kew Observatory, had laid the 

 foundations for the modern laws of radiation. 

 The new undergraduate became Senior Wrangler 

 and first Smith's Prizeman in 1865, and next year 

 was elected to a fellowship. His first scientific 

 paper, published in i86g, illustrated electro- 

 dynamic laws by comparison with those of 

 mechanical models, a method much used by Max- 

 well in his own papers. Next year his paper on 

 "Resonance" appeared, and this was the fore- 

 runner of a long series ot experimental and theo- 

 retical papers on vibrations in general, which, 

 when embodied in his "Theory of Sound," made 

 that work unique. 



In 187 1 the Cavendish Professorship of Experi- 

 mental Physics was founded at Cambridge, and, 

 urged by Strutt, Maxwell became the first holder 

 of the chair. In 1873 Strutt succeeded his father 

 as Baron Rayleigh, and on the death of Maxwell 

 in 1879 became Cavendish professor. During the 

 intervening years his scientific work had been 

 chiefly in optics and hydrodynamics, and he had 

 published important papers on waves and on 

 diffraction gratings, while at the Cavendish 

 Laboratory his experimental work consisted 

 mainly in a continuation of the determinations of 

 electrical standards inaugurated- by Maxwell as a 

 member of the Electrical Standards Committee of 

 the British Association. Working, in the first 

 instance, with Dr. Schuster, and afterwards with 

 Mrs. Sidgwick, he showed that the B.A. ohm was 

 I per cent, too small, and established values for 

 the electrochemical equivalent of silver and for 

 the electromotive force of the standard Clark cell, 

 which have been confirmed by more recent 

 measurements. Under the instigation of Lord 

 Rayleigh, other determinations of fundamental 

 importance were made in the laboratory, such as 

 J. J. Thomson's work on the number of electro- 

 static units in the electromagnetic unit, and 

 Glazebrook's on the B.A. ohm. 



In addition to his work on electrical standards, 

 Lord Rayleigh continued his acoustical observa- 

 tions, and took up the subject of surface tension 

 and its influence on the behaviour of jets. He 

 resigned the Cavendish professorship in 1884, 

 having during his five years' tenure of the oflice 

 contributed fifty papers to the advance of science. 

 During the next three years his researches were 

 mainly on optics and on electricity In 1887 he 

 became a secretary of the Royal Society and pro- 

 fessor of natural philosophy at the Royal Institu- 

 tion, holding the former office until 1896, and the 

 latter until 1905. His lectures at the Royal In- 

 stitution invariably showed how thoroughly he 

 was master of any subject he presented, and how 

 skilled he was in devising new and simple experi- 

 ments to illustrate his statements. His work 

 during these years was in the first mstance mainly 

 on light, and included his "W^ave Theory of 

 Lisfht " contributed to the "Encyclopaedia Britan- 

 nica " in 1888. 



A little later Lord Rayleigh took up the 

 dynamical theory of gases and the question of the 

 stabilitv of the flow of fluids, then the densities 



