5Q Anniversary Meeting. [Nov. 30, 



tho provision he has been successful in making for future work, in 

 the investigation of properties of matter at lowest temperatures. 



ROYAL MEDAL. 

 Professor J. /. Thomson, F.E.8. 



Professor J. J. Thomson has distinguished himself in both mathe- 

 matical and experimental fields of work. His first essay on vortex 

 rings showed power of grappling with difficult problems, and added 

 to our knowledge concerning the encounter of rings which came 

 within a moderate distance of one another so as to deflect each others' 

 paths. 



His theoretical work in the borderland of chemistry and physics 

 has been very interesting and suggestive. His experimental work 

 lias likewise been mainly on the borders of chemistry and physics. 

 He has observed the large conductivity of many gases and vapours, 

 and proved the non-conducting power of several others, founding 

 on the conducting power of iodine vapour important speculations as 

 to its probable chemical constitution. 



He has also measured the specific resistance of various electrolytes, 

 under extremely rapid electric oscillations, by an ingenious and valuable 

 method, based on the partial opacity of semi-conducting matter to 

 electro-magnetic waves. Recently he has worked at the discharge 

 of electricity through rarefied gases, getting induced currents in 

 closed circuits in sealed bulbs without electrodes, and, in especial, 

 measuring to a first approximation the absolute velocity of the posi- 

 tive discharge through a long vacuum tube, proving that it was com- 

 parable with, though decidedly less than, the velocity of light. He 

 also gave an ingenious theory of the striae a theory which he has 

 since endeavoured, with some success, to extend to a large number of 

 electrical phenomena, the whole of electric conduction and induction 

 being regarded by him from the chemical side as a modified or inci- 

 pient electrolysis, or as concerned with electrolytic chains of mole- 

 cules or " Faraday tubes." 



Some of his recent mathematical work on the theory of electric 

 oscillations in spheres and cylinders, and in dumb-bell oscillators of 

 the kind used by Hertz, with reference to not only their oscillation- 

 frequency but also their damping efficiency, has been of much service 

 to experimental workers in those branches of physics. And, in 

 general, the effective manner in which he attacks any electrical 

 problem presenting itself, as evidenced by his book on Recent 

 Researches in Electricity and Magnetism, wherein he worthily carries 

 on into a third volume the great treatise begun by Clerk Maxwell, is 

 evidence of consummate ability combined with remarkable energy 

 ;ind power of work. 



