Preface vii 



own sake ; but the difficulty and labour of the undertaking, and the learning 

 and historical research that it involved, had hitherto warned off the men 

 most competent to discharge it. The zeal of Maxwell for his new Cavendish 

 foundation was not thus to be deterred. Already in July, 1874, we find 

 him writing from Glenlair to Mr Garnett (Life, p. 389) : 



In the MS. he appears to be familiar with the theory of divided currents and 

 also of conductors in series, but some reference to his printed paper [on the 

 Torpedo] is required to throw light on what he says. He made a most extensive 

 series of experiments on the conductivity of saline solutions in tubes, compared 

 with wires of different metals, and it seems as if more marks were wanted for 

 him if he cut out G. S. Ohm long before constant currents were invented. His 

 measures of capacity will give us some work at the Cavendish Laboratory, 

 before we work up to the point where he left it. His only defect is not having 

 Thomson's electrometer. He found out inductive capacity of glass, resin, wax, 

 etc. 



According to Mr Garnett (Life, p. 555) who was in a position to be 

 intimately acquainted with the facts: 



The amount of labour which Professor Maxwell bestowed on this work 

 during the last five years of his life can only be known to those who were 

 constantly in his company. Nearly all the MSS. he transcribed with his own hand, 

 the greater part being copied after midnight.... Every obscure passage or altera- 

 tion was the subject of a long and searching investigation: and many were the 

 letters written to the Librarian of the Royal Society and to scientific and literary 

 friends in different parts of the country, to gain information respecting the 

 meaning of obsolete words and symbols, or the history of individuals. And 

 besides this, and a comparison of Cavendish's results with those obtained by 

 subsequent investigators, Maxwell repeated many of Cavendish's experiments 

 almost in their original form, only employing modern instruments for the 

 purposes of measurement. 



The result of five years of continual application to the subject was the 

 volume published in October, 1879 by the Cambridge University Press, 

 a few weeks before the death of its Editor, and now reprinted in different 

 form. The introductory sketch prepared by Maxwell, probably at the end 

 of his task, gives a clear and most interesting summary of the electrical 

 work of Cavendish: the postscript dated 14 June, 1879, describing some 

 manuscripts on magnetism that had just come to hand, coincides with 

 the beginning of his final illness. 



There is perhaps no instance in the history of science in which the 

 unpublished records left by an investigator have been arranged and 

 elucidated with such minute fidelity. Careless though Cavendish was of 

 scientific reputation, intent on pressing on to new solitary achievement, 

 to the neglect of publication, due as it would seem as much to the habit of 

 continual postponement of final preparations for the press as to the 

 fascination of exercising his powers of discovery and even, as it has 



