vi Preface 



the University, signified his desire to build and furnish a Physical Laboratory 

 for Cambridge: and in prospect of that gift the Cavendish Professorship 

 of Experimental Physics was founded by Grace of the Senate in Feb. 1871. 

 In response to appeals from the prominent Cambridge men of the time, 

 including Stokes, W. Thomson, and Rayleigh, Clerk Maxwell was persuaded 

 to offer himself for the Chair. He was formally elected the following month, 

 after six years of retired study and investigation which doubtless had 

 matured and consolidated the intellectual interests of his life, including 

 the preparation of the Electricity and Magnetism (Feb. 1873) and the 

 Theory of Heat (1870). The Laboratory was planned and furnished under 

 Maxwell's direction, and formally handed over to the University in the 

 spring of 1874. It was not however until 1877 that the Chancellor had 

 completed his gift "by furnishing the Cavendish Laboratory with apparatus 

 suitable to the present state of science"; an equipment to which Maxwell 

 afterwards contributed many additions. Later, Lord Rayleigh, when 

 Chancellor of the University, devoted the proceeds of the award of a 

 Nobel Prize to provide for an urgent expansion of the Laboratory of which 

 he had himself been Director. 



The Electricity and Magnetism shows many marks of hurried final 

 consolidation with a view to immediate publication. It was said that the 

 pressing need of a textbook in the University was a paramount considera- 

 tion : there was no treatise of comparable depth and grasp at that time in 

 any language. And certainly under Maxwell's influence Cambridge was 

 the focus in which the new electrical ideas, inherited in outline from 

 Faraday, were developed and propagated, years before they were taken 

 up in other countries and thus became everywhere the mainspring of pro- 

 gress in physical science. Maxwell's own personal investigations during the 

 Cambridge period, in addition to a series of brilliant articles, now classical, 

 written for the Encyclopaedia Britannica, were concerned mainly with the 

 development of the other equally fundamental, but analytically much 

 more complex, subjects centring round the molecular theory of gases; in 

 this domain also he had previously (1860) been the originator of the modern 

 exact analysis, based on application of the mathematical principles of 

 statistics to the fortuitous dance of the innumerable molecules. 



According to Maxwell's biographers his chief continuous literary 

 occupation, for the five years from 1874 to his death in October, 1879, 

 was the editing of the Electrical Researches of Henry Cavendish. It had 

 been well known that Cavendish's papers, preserved in the possession of 

 his kinsman the Duke of Devonshire, contained a very remarkable and 

 even mysterious record of progress in electrical as well as chemical science, 

 effected a hundred years previously by a solitary investigator, of which 

 only fragments had been revealed by various men of science who had seen 

 the manuscripts. The publication of an adequate account of the researches 

 of Cavendish was a task obviously incumbent on British science, for its 



