764 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



to the electrolytic production of alkali, and 2 to valves for fluids. 

 He was an independent inventor of the zigzag method of winding 

 alternators, which the public knew under the name of Ferranti's 

 machine, which was manufactured under royalties payable to him. 

 He was interested even in devising such details as fuses and the sus- 

 pension pulleys with differential gearing by which incandescent lamps 

 can be raised or lowered. 



He gave evidence before a parliamentary committee on electric 

 lighting and discussed the theory of the electric transmission of 

 power, pointing out the advantage of high voltages. The introduc- 

 tion into England in 1881 of the Faure accumulator excited him 

 greatly. In his Presidential Address to the Mathematical and Physi- 

 cal Section of the British Association at York that year he spoke of 

 this and of the possibility of utilizing the powers of Niagara. He 

 also read Uyo papers, in one of which he showed mathematically that 

 in a shunt dynamo best economy of working was attained when the 

 resistance of the outer circuit was a geometric mean between the re- 

 sistances of the armature and of the shunt. In the other he laid down 

 the famous law of economy of copper lines for the transmission of 

 power. 



Helmholtz, visiting him again in 1884, found him absorbed in 

 regulators and measuring apparatus for electric lighting and electric 

 railways. " On the whole,"' Helmholtz wrote, " I have an impression 

 that Sir William might do better than apply his eminent sagacity to 

 industrial undertakings; his instruments appear to me too subtle to 

 be put into the hands of uninstructed workmen and officials. * * * 

 He is simultaneously revolving deep theoretical projects in his mind, 

 but has no leisure to work them out quietly. As far as that goes, I 

 am not much better off." But he shortly added, " I did Thomson an 

 injustice in supposing him to be wholly immersed in technical work; 

 he was full of speculations as to the original properties of bodies, 

 some of which were very difficult to follow ; and, as you know, he will 

 not stop for meals or any other consideration." And, indeed, Thom- 

 son had weighty things in his mind. He was revolving over the 

 speculations which later in the same year he was to pour out in such 

 marvelous abundance in his famous 20 lectures in Baltimore " On 

 molecular dynamics and the wave theory of light." These lectures, 

 delivered to 26 hearers, mostly accomplished teachers and professors, 

 were reported verbatim at the time and reprinted by him with many 

 revisions and additions in 1904. Of this extraordinary work, done at 

 the age of GO, it is difficult to speak. Day after day he led the 26 

 " coefficients " who sat at his feet through the mazes of solid-elastic 

 theory and the spring-shell molecule, newly invented in order to give 

 a conception how the molecules of matter are related to the ether 

 through which light waves are propagated. All his life he had been 

 endeavoring to discover a rational mechanical explanation for the 



