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



terrestrial phenomena involving radiation, had more recently rendered this 

 problem urgent. Following on various purely optical papers on the 

 phenomena of moving bodies, Prof. Lorentz, in 1892, elaborated a general 

 molecular treatment in the memoir " La Theorie Electro-magnetique de 

 Maxwell, et son Application aux Corps Mouvants," which appeared in the 

 ' Archives Neerlandaises,' and contains substantially the main root ideas of 

 the subject. In 1905 it was re-expounded with further development in a 

 tract entitled " Yersuch einer Theorie der Electrischen und Optischen 

 Erscheinungen in Bewegten Korpern," the main feature being the elimina- 

 tion of the dynamical element in the previous discussion in favour of a 

 formulation by a system of abstract equations, after the way first set out by 

 Maxwell himself as a summary of his final definite results as distinct from 

 the formative ideas underlying them, and afterwards brought into prominence 

 by the expositions of Heaviside and Hertz. 



By these writings Prof. Lorentz has taken a predominant place in the 

 modern evolution of electric and optical theory. He has since been active 

 in special applications, of which the best known has been his theoretical 

 prediction of the physical features of the alteration of the lines of the 

 spectrum in a magnetic field, which had been discovered and has since been 

 developed by his colleague Zeeman. 



Royal Medals. 



The assent of His Majesty the King, our Patron, has been graciously signified 

 to the following awards of the Medals presented annually by him to the Society. 



A Eoyal Medal to Prof. John Milne, F.R.S., for his work on Seismology. 

 In 1875, Dr. Milne accepted the position of Professor at Tokyo, which 

 was offered to him by the Imperial Government of Japan. His attention 

 was almost immediately attracted to the study of earthquakes, and he was 

 led to design new forms of construction for buildings and engineering 

 structures with a view to resisting the destructive effects of shocks. His 

 suggestions have been largely adopted, and his designs have been very 

 successful for the end in view. Incidentally he studied the vibrations of 

 locomotives, and showed how to obtain a more exact balancing of the moving 

 parts, and thus to secure smoother running and a saving of fuel. Here 

 again his suggestions were accepted, and his work was recognised by the 

 Institution of Civil Engineers. 



He next devoted himself to the study of artificial shocks produced by the 

 explosion of dynamite in borings. He then studied actual shocks as 

 observed at nine stations connected by telegraph wires. A seismic study of 

 Tokyo, and subsequently of the whole of northern Japan, followed. In this 



