88 Anniversary Address by Lord Rayleigh, [Nov. 30, 



increasing specialisation of science, in rendering really useful the reading of 

 papers and discussions thereupon. It is, of course, felt more severely in a 

 Society like our own, which embraces within its scope the whole scientific 

 field. It not infrequently happens that a paper is addressed to an audience 

 among whom there is no one competent to follow the detailed observations 

 and reasonings of the author. I am sometimes reminded of a saying of 

 Dalton's on similar occasions at Manchester, quoted by Sir Henry Eoscoe in 

 his genial and entertaining ' Eeminiscences ' : " Well, this is a very interesting 

 paper for those that take any interest in it." A little more discretion on the 

 part of readers of papers in having regard to the composition of their actual 

 audience would be helpful here. In some cases experimental illustration 

 would bring home to a larger number what is followed with difficulty from a 

 merely verbal statement. But I am afraid that no complete remedy is 

 within reach. 



Increase of specialisation, however inconvenient in some of its aspects, 

 is, I suppose, a necessary condition of progress. Sometimes a big discovery, 

 or the opening up of a new point of view, may supersede detail and bring 

 unity where before there was diversity, but this does not suffice to com- 

 pensate the general tendency. Even in mathematics, where an outsider 

 would probably expect a considerable degree of homogeneity, the movement 

 towards diversity is very manifest. Those who, like myself, are interested 

 principally in certain departments, and can look back over some 40 years, 

 view the present situation with feelings not unmixed. It is disagreeable 

 to be left too far behind. Much of the activity now displayed has, indeed, 

 taken a channel somewhat remote from the special interests of a physicist, 

 being rather philosophical in its character than scientific in the ordinary 

 sense. Much effort is directed towards strengthening the foundations upon 

 which mathematical reasoning rests. No one can deny that this is a 

 laudable endeavour; but it tends to lead us into fields which have little 

 more relation to natural science than has general metaphysics. One may 

 suspect that when all is done fundamental difficulties will still remain to 

 trouble the souls of our successors. Closely connected is the demand for 

 greater rigour of demonstration. Here I touch upon a rather delicate 

 question, as to which pure mathematicians and physicists are likely to differ. 

 However desirable it may be in itself, the pursuit of rigour appears some- 

 times to the physicist to lead us away from the high road of progress. He 

 is apt to be impatient of criticism, whose object seems to be rather to pick 

 holes than to illuminate. Is there really any standard of rigour independent 

 of the innate faculties and habitudes of the particular mind ? May not 

 an argument be rigorous enough to convince legitimately one thoroughly 



