NOTES 287 



In 1904 he was awarded the Nobel Prize ; the Royal Society- 

 gave him the Copley, the Royal, and the Rumford medals ; 

 he was an Officer of the Legion of Honour, Foreign Member of 

 the Institute of France, and of many British and Foreign 

 Scientific Societies, while he received degrees from numerous 

 Universities at home and abroad. 



His papers from about 1870 to 19 10 are contained in the 

 five volumes of Collected Works, and to the 349 there printed 

 others have been added since, which must bring the total well 

 over 400. They cover the whole range of Mathematical Physics, 

 and, to quote Sir J. J. Thomson's appreciative article in Nature 

 for July 10 last, " Not one of these is commonplace, there is not 

 one which does not raise the level of our knowledge of the 

 subject." Besides these there is the great book on Sound, which 

 has done more than any other work on the subject to put the 

 fundamental laws of acoustics on a firm basis. 



A number of the earlier papers deal with optical questions, 

 and these continued to have a special interest for Lord Rayleigh 

 till the end. The last time the writer saw him at Terling, he 

 was working at the colours of beetles' wings, and was much 

 interested in the difficulties of the problem. The papers deal 

 with the scattering of light by small particles, and by showing 

 that the intensity of the scattered light is inversely propor- 

 tional to the fourth power of the wave length, give a rational 

 account of the blue of the sky ; the molecules of air are small 

 enough to scatter some of the incident rays and deflect the blue 

 rays much more copiously than the red. About this time, too, 

 the theory of double refraction attracted him, and he investi- 

 gated the question whether this could be explained by an selo- 

 tropic distribution of inertia rather than of elasticity, as had been 

 assumed by older writers. It was shown that, if the ether be 

 treated as incompressible, the assumption led to a form of wave 

 other than that of Fresnel. This was, of course, before the 

 days of Maxwell's Electromagnetic Theory. 



During the same period the Theory of Sound appeared ; 

 the first volume was published in 1877. It deals mainly with 

 vibrating systems in general, and well bears out the claim 

 made by its author in his preface for some novelty of treatment 

 and results. The second volume appeared the following year. 



Then came the Cambridge period 1 879-1 884. The Cavendish 

 Laboratory had been opened in 1871 with Maxwell as the first 



