5o6 POPULAR LECTURES AND ADDRESSES. 



a general survey of Faraday's work during his 

 fifty-four years' connexion with the Royal Institu- 

 tion was given. Naturally, a large part of the 

 lecture was devoted to magnetism and electricity 

 and to electro-magnetic induction ; but it con- 

 tained also much that must have been surprising 

 to the audience, scarcely prepared to be told, 

 as they were told by Lord Rayleigh, that 

 " Faraday's mind was essentially mathematical 

 in its qualities," and that, particularly in his 

 acoustical work, he had made many very acute 

 observations of physical phenomena, of a kind to 

 help in guiding the mathematician to the solution 

 of difficult and highly interesting problems of 

 mathematical dynamics, and in some cases 

 actually to give him the solution surprisingly 

 different from what might have been expected 

 even by highly qualified mathematical investi- 

 gators. 



The other Faraday Lecture, given by Professor 

 Dewar, was a splendid realisation of Faraday's 

 anticipations regarding the liquefaction of the 

 " permanent gases," according to which no ex- 



