December 8, 192 1] 



NATURE 



473 



of mathematical physicists and experimental physicists, 

 it is refreshing to come across one who was each — 

 who, like Kelvin and Stokes, was each and all of 

 these. Lord Rayleigh took physics for his province 

 and extended the boundary of even.* department of 

 physics. The impression made by reading his papers 

 is not only due to the beauty of the new results 

 attained, but to the clearness and insight displayed, 

 which gives one a new grasp of the subject. No sub- 

 ject passed through Lord Rayleigh 's mind without 

 being clarified and having its difficulties either re- 

 moved or brought so strongly into the light as to be 

 subject to attack on every side. 



The impression that one gets after reading a paper 

 by Lord Rayleigh is that the subject, if I may use a 

 homely phrase, has been tidied-up. Law and order 

 have been substituted for disorder. There are some 

 great men of science whose claim consists in having 

 said the first word on a subject, in having introduced 

 some new idea which has proved fruitful ; there are 

 others whose claim consists perhaps in having said 

 the last word on the subject, and who have reduced 

 the subject to logical consistency and clearness. I 

 think by temperament Lord Rayleigh really belonged 

 to the second group. Certainly no man ever revelled 

 more in that greatest of intellectual pleasures, work- 

 ing at a subject which was all obscured and tangled 

 and bringing it to a stage where ever\-thing was clear 

 and in order. When we take Lord Rayleigh 's papers 

 we find some purely mathematical, in which, with his 

 characteristic directness of attack and simplicit].' of 

 means, he obtained most important results. We get 

 others almost purely experimental, such as the deter- 

 mination of the absolute unit in electricity, in which, 

 again, with simple apparatus, he attained results which 

 rivalled in accuracy those of Regnault and Joule. 

 But in the majority of w^ritings we have a combina- 

 tion of mathematical analysis and experimental work, 

 and his papers, I think, afford the best illustration 

 of the true co-ordination of those two great branches 

 of attack on the problems of nature. The physical 

 ideas direct the mathematical analysis into the 

 shortest and most appropriate channels, while 

 the mathematics gives precision and point to the 

 physics. 



Just one word about another characteristic of Lord 

 Rayleigh. He was, so to speak, the knight-errant of 

 physics. There are men of whom it is said that they 

 never shirk a difficulty, but Lord Rayleigh went 

 roaming about seeking for difficulties to destroy, and 

 I really believe that he loved a difficulty for its own 

 sake, and perhaps felt sorn,' for it after he had de- 

 stroyed it. But among the difficulties in physics 

 none was ever created by any default of Lord Ray- 

 leigh in clearness of expression or clearness of thought. 

 He was an artist in the production of his papers. 

 He had the artist's instinct ingrained so deeply that 

 even the excitement and hurry of the Cambridge 

 Mathematical Tripos in the old days, when it was 

 literally a race against time, could not destroy it. 

 Ever\- one of his examiners on that occasion said that 

 his papers were so clear that they could have been 

 sent to press vvithout revision. 



Among Lord Rayleigh 's many discoveries I will 

 just confine myself to one, the discoverv of argon, 

 because that is the one which attracted most 

 attention, and in which, perhaps, he broke the newest 

 ground. The discovery of argon is one of the 

 romances of science. The fact was that we had, 

 unsuspected among us, the element in large propor- 

 tions — there are, I believe, some tons of it within the 

 walls of this building — and yet, in spite of the experi- 



NO. 2719, VOL. 108] 



ments of chemists and physicists for centuries no 

 suspicion of its existence had ever arisen. It seems 

 rather an irony that while the chemists had been 

 ransacking mines and searching the stars for new 

 elements, all the time there had been in their labora- 

 tories an element with more remarkable properties 

 than any that had been discovered. The remarkable 

 thing about Lord Rayleigh 's investigation was that 

 it was not because he used instruments more powerful 

 than any of those at the command of his predecessors. 

 Argon was' tracked down by the oldest piece of 

 chemical apparatus, the balance, an instrument which 

 had been at the command of all Lord Rayleigh 's pre- 

 decessors, and by which they might have made the 

 discover}-, but they did not. In the isolation of argon 

 Lord Rayleigh was fortunate enough to procure the 

 co-operation of Sir William Ramsay, and when the 

 properties of the new substance were investigated 

 they turned out to be o? extraordinary interest, and 

 the discovery of this, which was followed by the 

 discovery of other gases of the same nature, has had 

 a very pronounced influence on the progress of our 

 ideas as to the structure of matter. 



I must pass on from Lord Rayleigh 's contributions 

 to science to consider some of his" public ser\-ices. 

 He was long and intimately connected with the Roval 

 Society. For nine years he was secretar}-, and for 

 three years he was president. He enriched the 

 publications of that society by papers which added 

 greatly to its prestige. He rendered great services 

 to the University of Cambridge. On Maxwell's death 

 in 1879, when the success of the new School of 

 Physics was not yet assured, Lord Rayleigh, at con- 

 siderable personal sacrifice, came to the rescue, and 

 for five years he was the Cavendish Professor of 

 Physics, and this work, with the assistance of thai 

 of Sir Richard Glazebrook and of Sir Napier Shaw, 

 put the school on such a firm basis that its success 

 has never since been in doubt. The University- took 

 the opportunity of honouring Lord Rayleigh by 

 making him their chancellor; but it was' not only 

 work that Lord Rayleigh gave to the University : he 

 was a generous benefactor. When he received the 

 Nobel prize he handed over the money for the use 

 of the University. Again, he was long connected 

 with the Royal Institution. He was professor there 

 for seventeen years, and many of us have heard those 

 clear explanations of some of the most difficult 

 problems of physics, accompanied by experi- 

 ments, which were characteristicallv simple and 

 beautiful. 



But of all the bodies with which Lord Rayleigh was 

 associated I doubt if there was one in which he was 

 more interested than in the National Physical Labora- 

 tor)-. He was the chairman of the committee which 

 recommended the foundation of that institution, and 

 he w-as chairman of the executive body from the be- 

 ginning until a year or two before his death. The 

 growth of that institution from very small beginnings 

 to the position it now occupies, that of the most 

 important institution of its kind in the world, is due 

 in no small degree to the work that Lord Ravleigh 

 gave to it, to the judgment that he displayed iii con- 

 ducting its affairs, to his knowledge, and to his in- 

 fluence. 



Another subject in connection with which Lord 

 Rayleigh rendered great ser\'ices was that of flight. 

 He was convinced long before other people of the 

 possibilit>', and even the probability, of flight, and 

 when flight became a serious problem to this countri* 

 he became chairman of the Committee on Research 

 in Aeronautics, and it meant everj'thing to that sub- 



