xvi PKEFACE. 



This is also borne out by the fact that he was soon afterwards elected Professor of 

 ural Philosophy and Astronomy in King's College, London. The new appointment had 

 the advantage of bringing him much more into contact with men in his own department 

 of science, especially with Faraday, with whose electrical work his own was so intimately 

 connected. In 1862 63 he took a prominent part in the experiments organised by a 

 Committee of the British Association for the determination of electrical resistance in 

 absolute measure and for placing electrical measurements on a satisfactory basis. In the 

 experiments which were conducted in the laboratory of King's College upon a plan due 

 to Sir W. Thomson, two long series of measurements were taken in successive years. In 

 thr first year, the working members were Maxwell, Balfour Stewart and Fleeming Jenkin ; in 

 th.- second, Charles Hockin took the place of Balfour Stewart. The work of this Committee 

 was communicated in the form of reports to the British Association and was afterwards 

 republished in one volume by Fleemiug Jenkin. 



Maxwell was a professor in King's College from I860 to 1865, and this period of his 

 liti- is distinguished by the production of his most important papers. The second memoir 

 on Colours made its appearance in 1860. In the same year his first papers on the Kinetic 

 Theory of Gases were published. In 1861 came his papers on Physical Lines of Force 

 and in 1864 his greatest memoir on Electricity, a Dynamical Theory of the Electro- 

 magnetic Field. He must have been occupied with the Dynamical Theory of Gases in l>S(i">. 

 as two important papers appeared in the following year, first the Bakerian lecture on the 

 Viscosity of Gases, and next the memoir on the Dynamical Theory of Gases. 



The mental strain involved in the production of so much valuable work, combined 

 with the duties of his professorship which required his attention during nine months of 

 the year, seems to have influenced him in a resolution which in 1865 he at length 

 adopted of resigning his chair and retiring to his country seat. Shortly after this he had 

 a severe illness. On his recovery he continued his work on the Dynamical Theory of 

 Gases, to which reference has just been made. For the next few years he led a quiet 

 and secluded life at Glenlair, varied by annual visits to London, attendances at the British 

 Association meetings and by a tour in Italy in 1867. He was also Moderator or Examiner 

 in the Mathematical Tripos at Cambridge on several occasions, offices which entailed a fr\\ 

 weeks' residence at the University in winter. His chief employment during those years 

 \\a^ the preparation of his now celebrated treatise on Electricity and Magnetism which, 

 however, was not published till 1873. He also wrote a treatise on Heat which was 

 published in 1871. 



In 1871 Maxwell was, with some reluctance, induced to quit his retreat in the 

 country and to enter upon a new career. The University of Cambridge had recently 

 resolved to found a professorship of physical science, especially for the cultivation and 

 teaching of the subjects of Heat, Electricity and Magnetism. In furtherance of this 

 object her Chancellor, the Duke of Devonshire, had most generously undertaken to build 

 a laboratory and furnish it with the necessary apparatus. Maxwell was invited to fill the 



