2 8 SECTIONAL ADDRESSES 



departments and a staff of a hundred and twenty-six, is Glazebrook's 

 enduring monument. 



The work of this great laboratory, stimulated by the conditions of 

 the world-war, was further developed by Sir Joseph Petavel ; under 

 his guidance the laboratory has steadily grown in prestige and in the 

 range of its activities, which now demand the services of a staff of nearly 

 seven hundred. In the counsels of our Association, Sir Joseph Petavel 

 ranked as an engineer — he presided in 191 9 over the work of Section G — 

 but we of this Section are not unmindful of his contributions to physical 

 science : of his studies of the emissivity of platinum at high temperatures, 

 of the effect of pressure on arc-spectra, of his interest in the problem 

 of aeroplane stability. 



Genius, both in its creative aspect and on that side which has been 

 condensed by Edison into a whimsical phrase, marked all to which Karl 

 Pearson put his hand. His ordered development of statistical theory 

 wherein new light is shed on the fundamental problems of frequency 

 distribution, correlation, and probable errors, formed a firm foundation 

 for a superstructure impressive in its height and extent ; he never lost 

 that early interest in elasticity shown in his completion of Todhunter's 

 massive History of the Theory of Elasticity ; and his Grammar of Science, 

 overlooked by the majority of our present-day physical-philosophers 

 (though there is perceptible a movement in a direction which shows that 

 its thesis is again finding favour), develops a point of view which should 

 not prove unhelpful to the student of to-day who would fain remain 

 a physicist without of necessity becoming a metaphysician. 



These men, whose memories we honour to-day, were trained in a 

 tradition which differs toto coelo from that in which our present generation 

 lives and moves. It seems, therefore, not unfitting that one of the 

 presidents whom you have honoured by election to this chair should 

 endeavour to put before you a picture which may show something of 

 these changes and tell something of the facts that have caused them — 

 if it be permissible to use a phrase which apparently commits one to a 

 deterministic outlook. 



The world-picture of the older generation was, as we look back on it 

 to-day, extraordinarily simple. It is, or has been, the fashion to describe 

 nineteenth-century science as materialistic. There certainly was Buchner, 

 and there was Tyndall's Belfast address. But D?-. Stoffkraft had neither 

 a long reign nor an influential following, and we shall be nearer to the 

 truth if we look upon Victorian science as showing a simple realism — 

 the realism of the man in the street — not wholly unrelated to that simple 

 realism of to-day which sees in an alpha-ray track evidence for the existence 

 of an atom of the same order as that furnished by a diffraction photograph 

 (or, for that matter, of our own eyes) for the existence of a star. 



That is by no means the whole story, as far as Victorian science is 

 concerned — Karl Pearson tells a very different tale ; but more of that 

 later. 



What we have learned to call the classic outlook was based on those 

 notions of velocity, acceleration, momentum and force which were 

 first formed into an ordered scheme by the genius of Newton — a scheme 



