A— MATHEMATICAL AND PHYSICAL SCIENCES 41 



knowledge of contact-angles — a rather neglected subject — is of great 

 importance, and during the last year or two, much attention has been 

 given to the measurement of contact-angles and to the application of the 

 results to flotation processes. Indeed, a knowledge of surface-constants 

 has many applications to industrial and to purely scientific problems, 

 and it may not be out of place to draw attention to the curious shape of 

 the curves showing the march of surface tension with temperature for 

 certain crystalline liquids. 



A most interesting application of classical atomic physics has recently 

 been made in certain extensions of the theory of the Brownian movement. 

 Measurements have been made of the Brownian movement of delicately 

 suspended balances, movements due, of course, not to mass-motion of air 

 or draughts but to irregular molecular bombardment, and a remarkably 

 good value of Avogadro's number results from a determination of the 

 amplitudes of such movements. Obviously if instruments become so 

 delicate that their Brownian motion is appreciable, it becomes possible 

 that Brownian motion may set a limit to the use of the instrument ; this 

 question has recently received consideration. 



Electron diffraction has been applied with success to problems in 

 technical physics. The very small penetration of even the swiftest 

 electrons employed makes them peculiarly suitable for the study of surface 

 structure, and the method has been used to attack such problems as the 

 poisoning of oxide-coated filaments, and the study of lubrication. 



Of the remarkable progress made in low-temperature research, we shall 

 hear during the meeting of the Section. One other matter may be 

 mentioned in passing — the development of precision methods in calori- 

 metry which may make it possible to study accurately the temperature- 

 variation of the specific heats of liquids (deuterium oxide, for example) 

 available only in small quantities. 



Of recent years our Association has concerned itself more and more 

 with a study of the repercussions of the advancement of science on the 

 fabric of our society. Never in the history of mankind have more 

 powerful weapons for good and for evil been placed in the hands of the 

 community as a direct result of the growth of scientific knowledge ; and 

 never has it been more necessary for the scientist to develop some awareness 

 of the effects of his activities on the well-being of that community of which 

 he himself is a responsible member. 



We are most of us ready enough to discuss the ' Impact of Science on 

 Society,' so long as we restrict ourselves to an enumeration of the benefits 

 which science has bestowed upon mankind ; and on occasion we may 

 make a rather snobbish distinction between cultural and vocational 

 values. But we have to remember actively that there are dysgenic appli- 

 cations of scientific knowledge, and if the scientist claims, as he rightly 

 does, that place in the counsels of the nation which the importance of his 

 work warrants, he must cease his worship of what Professor Hogben calls 

 the ' Idol of Purity,' must be prepared to discuss all the social implications 

 of his work and to educate himself, as well as his less fortunate brethren 

 trained in the humanity schools, in a knowledge of these implications. 



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