234 Professor- Joseph Larmor [May 1, 



mission over long distances, as communicated in the form of evidence 

 to a Paiiiamentaiy Committee two years before. The brief paper, 

 now classical in electro-technics, then communicated,* ' On the 

 Economy of Metal in Conductors of Electricity,' is an early notable 

 instance of the blending of economics with exact physics : the solution 

 of the problem " would be found by comparing the annual interest of 

 the money value of the copper with the money value of the energy 

 lost annually in the heat generated in it by the electric current. The 

 money value of a stated amount of energy had not yet begun to 

 appear in the city price hsts." He shows that the gauge to be chosen 

 for the transmitting conductor does not depend on its length, but 

 solely on the strength of the current to be employed. He was much 

 concerned also in the early evolution of dynamos (the term had been 

 introduced by him about this time as a contraction for dynamo-electric 

 machine), the designing of which was to become entirely effective a 

 few years later by means of the graphical methods introduced by 

 Hopkinson. Perhaps the earUest domestic installation of electric 

 hghting in this country was the experimental one which he establislied 

 in his house at the University of GlasgoAv ; while one of the early 

 public installations was the one, still in operation, which he presented, 

 in connection with the celebration of the six hundredth anniversary of 

 the foundation of that most ancient house, to his College in Cambridge, 

 which had been able, under new statutes, to re-elect him to the 

 Fellowship that he had vacated long before on his marriage. 



■ The introduction of heavy cuiTents and voltages in engineering 

 required the provision of suitable instruments of measurement. This 

 was always a congenial task : his graded series of current- weighers or 

 ampere-meters, and of volt-meters — embodying those theoretical 

 principles of adequate support free from constraint or strain, in 

 mechanical design, on which he always insisted, to the great improve- 

 ment of general practice in such matters — have proved to be of funda- 

 mental service wherever exact measurement is essential. 



His interests rami lied into all departments of human activity : 

 even his physical writings were often relieved l)y play of allusion to 

 literature and history. In his later years he took an active and 

 zealous part in political affairs, and attended regularly the sittings of 

 the House of Lords. In his undergraduate days he was one of the 

 founders of the Cambridge University Iklusical Society, playing the 

 French horn at its opening concerts in 1843, and becoming president 

 in due course. Later he published some observations f on the beats of 

 imperfect harmonies of simple tones, tending to a conclusion different 

 from that of Helmholtz which referred the beats to combination tones. 



All this activity implied a robust constitution. As an under- 

 graduate at Cambridge, he found time to take a keen interest in 



* Brit. Assoc. Report, 1881, pp. 526-8. 

 t Roy. Soc. Edin. Proc, 1878. 



