clviii MEMOIR 



and it is no small thing to be proud of in respect to Jenkin's fame 

 as a scientific and practical electrician that the microfarad which 

 we now all use is his. 



The British Association unit of electrical resistance, on which was 

 founded the first practical approximation to absolute measurement 

 on the system of Gauss and Weber, was largely due to Jenkin's zeal as 

 one of the originators, and perseA r ering energy as a working member, 

 of the first Electrical Standards Committee. The experimental 

 work of first making practical standards, founded on the absolute 

 system, which led to the unit now known as the British Association 

 ohm, was chiefly performed by Clerk Maxwell and Jeiikin. The 

 realisation of the great practical benefit which has resulted from 

 the experimental and scientific work of the Committee is certainly 

 in a large measure due to Jenkin's zeal and perseverance as secretary, 

 and as editor of the volume of Collected Reports of the work of the 

 Committee, which extended over eight years, from 1861 till 1869. 

 The volume of Reports included Jenkin's Cantor Lectures of January 

 1866, * On Submarine Telegraphy,' through which the practical ap- 

 plications of the scientific principles for which he had worked so 

 devotedly for eight years became part of general knowledge in the 

 engineering profession. 



Jenkin's scientific activity continued without abatement to the 

 end, as will be seen by the detailed account of his published papers 

 contained in the present volume. For the last two years of his life 

 he was much occupied with a new mode of electric locomotion, a 

 very remarkable invention of his own, to which he gave the name of 

 ' Telpherage.' He persevered with endless ingenuity in carrying 

 out the numerous and difficult mechanical arrangements essential 

 to the project, up to the very last days of his work in life. He had 

 completed almost every detail of the realisation of the system which 

 was recently opened for practical working at Glynde, in Sussex, four 

 months after his death. 



His book on ' Magnetism and Electricity,' published as one of 

 Longman's elementary series in 1873, marked a new departure in 

 the exposition of electricity, as the first text-book containing a 

 systematic application of the quantitative methods inaugurated by 

 the British Association Committee on Electrical Standards. In 

 1883 the seventh edition was published, after there had already 

 appeared two foreign editions, one in Italian and the other in 

 German. 



His papers on purely engineering subjects, though not numerous, 



