56 JAMES CLERK MAXWELL 



the way of absolute electrical measurement since that 

 date; while Appendix D gives an account by tho 

 same two workers of the experiments on tho absolute 

 unit of electrical resistance made in the laboratory of 

 King's College by Maxwell, Fleeming Jenkin, and 

 Balfour Stewart. Further experiments are described 

 in the report for 18G4. Tho work thus begun was 

 consummated during tho year 1804 by tho legalisation 

 throughout the civilised world of a system' of electrical 

 units based on those described in these reports. 



Meanwhile, Maxwell's views on electro-magnetic 

 theory were quietly developing. Papers on "Physical 

 Lines of Force," which appeared in the PhUn^t^tttcal 

 Magazine during 1801 and 1802, contain the germs 

 of his theory expressed at that time, it is true, in a 

 somewhat material form. In tho paper published 

 January, 1802, the now well-known relation between 

 the ratio of tho electric units and tho velocity of light 

 was established, and his correspondence with Fleeming 

 Jenkin and C. J. Munro about this time relates in 

 part to the experimental verification of this relation. 

 His experiments on this matter were published in tho 

 "Philosophical Transactions" for 180S. 



This electrical theory occupied his mind mainly 

 during 186'} and 1804. In September of the latter 

 year he writes* from Glenlair to C. Mock in, who had 

 taken Balfour Stewart's place during the second scries 

 of experiments on the measurement of resistance. 



" I have been doing several electrical problems. I have got 

 a theory of 'electric absorption,' i>. f residual charge, etc., and 

 I very much want determinations of the specific induction, 



* " Life of J. C. Maxwell," p. 310. 



