Febniary ijth, ipoo.] PROCEEDINGS. xv 



Special Meetinp;, February i3tli, 1900. 



Horace Lamb, M.A., LL.D., I-\R.S., I'resident, in the Chair. 



Th > President, in making the presentations of the Wilde and 

 Dallon medals, and of the Wilde premium, said: 



"'Hie Wilde Medal for 1900 is awarded to Lord Rayleigh, 

 for his numerous and brilliant contributions to Mathematical and 

 Experimental Physics, and to Chemistry. 'Phese extend over 

 so wide a field that it is difficult to make a selection which, with- 

 out being too long, shall escape the risk of omitting things equally 

 important with those specially commemorated. Accepting this 

 risk, however, mention may be made, in the department of 

 Mathematical Physics, of his investigations on the general theory 

 of Vibrations, which are included with many other original 

 matters in the great work on 'Sound'; on the theory of Diffraction 

 in Optics, and its bearing on the resolving power of optical 

 instruments ; on the scattering of light by small particles ; on 

 Waves in Liquids ; on Capillary Phenomena; on the approximate 

 calculation of electrical and other constants; and on the distribu- 

 tion of alternating currents in conductors. And in this Society, 

 which claims a share in the early history of Thermodynamics 

 and of the Theory of Gases, it would be specially inexcusable to 

 pass over the highly original work which Lord Rayleigh has 

 done and is still doing in this connection. 



His experimental investigations have been closely connected 

 with the tlieoretical researches above referred to. Special mention 

 may perhaps be made of the classical electrical determinations 

 made in the Cavendish Laboratory at Cambridge, and of a long 

 series of papers on the superficial phenomena of liquids, inclu- 

 ding the elucidation of the nature of superficial viscosity. 



Li Chemistry, again. Lord Rayleigh's discoveries are the 

 result of his theoretical investigations. From the theory of thin 

 spherical elastic shells he deduced a correction which must be 

 applied in the weighing of gases in glass globes by Regnault's 

 method. 'Phis correction enabled him to determine experi- 

 mentally the true densities of oxygen and hydrogen, and 

 finally to establish beyond doubt the atomic weight of oxygen. 

 In determining the density of nitrogen by this method, he first 



