LORD KELVIN 299 



his quadrant electrometer, which soon became indispensable, 

 together with various forms of direct reading ammeters, 

 which at that time were a complete novelty, and his exact 

 appliances for investigating atmospheric electricity; further- 

 more, his improvements in the ship's compass and ap- 

 paratus for taking soundings. But one of his most important 

 inventions was his receiving apparatus for cable telegraphy 

 (1867), the well-known siphon recorder, which for a long- 

 time was used exclusively for reception from long dis- 

 tances; such reception was only made possible by its use.^ 

 These achievements, so rapidly made and of such general 

 interest, no doubt gave much satisfaction to Thomson him- 

 self, though they could only be for him a subsidiary matter; 

 but they had without doubt the greatest influence upon his 

 public reputation and also upon his elevation to the peerage, 

 which occurred in 1892, when he took the title of Lord 

 Kelvin. They also enabled him to maintain a large country 

 house and a yacht. A wife who always took the greatest care 

 of his well-being was his lifelong companion. At seventy- 

 five he gave up teaching; he died at the age of eighty-four. 



A particularly important achievement of Thomson's was 

 his first calculation of electric oscillations. He was the first 

 to make clear how the self-induction of a circuit discovered 

 by Faraday must result in the production of alternating 

 electric currents in an open circuit of conductors, and he 

 had calculated in every detail, from the law of induction 

 and Ohm's law, the nature of such oscillations; that is to say 

 their period, damping, and the whole course of their in- 

 tensity, as dependent upon the capacity, self-induction and 

 resistance. 2 



Such oscillations, the existence of which had already been 

 suspected by Helmholtz, could then actually be produced 



^The laying of the cable, which was also not a simple matter was first 

 successfully accomplished by Werner Siemens; see his memoirs. 

 2 Philosophical Magazine, Vol. 5, p. 393, 1853. 



