6i4 



NATURE 



[Oct. 24, 1889 



Faraday. The law of the motion of heat had not only 

 been experimentally determined, but had been theo- 

 retically discussed by Fourier. The specific heats of the 

 elementary bodies, as well as the heat developed in com- 

 bination, had to some extent been determined by Dulong. 

 And the law connecting the quantity of electricity pro- 

 duced in voltaic batteries with the number of chemical 

 elements separated, had been discovered by Faraday. 

 So far, however, these various branches of physics and 

 chemistry had been subjects of separate and distinct 

 study. No suggestion of equivalence had been made 

 between the heat of combination of the elements and the 

 electric current that would be produced by the same 

 combination effected in the battery. That heat was 

 developed in conductors by electric currents was known, 

 but again there had been no suggestion of an equivalence 

 between the heat and the resistance overcome. What 

 are now known as the dynamo and motor had been 

 invented by Sturgeon, showing that work could be done 

 by the agency of electricity and electric separation effected 

 by the agency of work, but again no equivalence between 

 the amount of work and the energy of combination of 

 the element in the battery had been surmised. 



It was for Joule not only to suggest all these equiva- 

 lences, but to experimentally determine all their numerical 

 values ^ before he came to the equivalence of the work - 

 spent in overcoming fluid, or solid, friction and the heat 

 produced ; and, again, between the work spent in com- 

 pressing air and the heat produced. 



The discovery of the mechanical equivalent of heat, 

 important as it is, is but a poor expression for the outcome 

 of this work, in which Joule converted what had till 

 then seemed unquestionable cases of the destruction of 

 energy into the most striking cases of its indestructibility. 

 And although he propounded no theory, but simply 

 declared himself to have believed in the indestructibility 

 of vis-viva, or living force, he had, in the truest sense of 

 the word, discovered the universal law that energy is in- 

 destructible and uncreatable. As Joule's work came to be 

 apprehended, this law became accepted as its natural con- 

 sequence in greater and greater significance, until now it 

 stands the most general recognized law in the universe ; 

 relating not only to all matter but also the medium of 

 space, which is thus found to possess the mechanical 

 properties of matter and to be subject to the laws of 

 motion. 



The discovery of this law, bringing as it does the several 

 branches of physical science into the domain of mechani- 

 cal philosophy, fitly crowned all the work in physical 

 science of the previous 150 years, of which it was the 

 result. It also opened out a fresh platform for further 

 discoveries — a platform which was immediately occupied in 

 the erection of the compound sciences of thermodynamics, 

 electrodynamics, and the dynamical theory of gases. 



Joule was never prominently before the public. Ready 

 to give himself with absolute devotion to the cause of 

 science and the advancement of human knowledge, he 

 yet preferred retirement and the calm labour of his 

 laboratory to the excitement of public lectures and de- 

 monstrations. While he was keenly alive to the sym- 

 pathy of friends, yet he worked for the most part alone. 



or in conjunction with one or other of the friends men-| 

 tioned in the earlier part of this notice. He sought not' 

 at all for fame, but only for truth. 



And yet honours in plenty came to him. He received 

 honorary degrees from the most important Universities ; 

 he was honorary Fellow of many learned Societies' 

 at home and abroad. He was a Fellow of the Royal 

 Society, and received from it the Gold Royal Medal ia 

 1852, and the Copley Gold Medal in 1870. The Albert 

 Medal of the Society of Arts was delivered to him from 

 the hands of the Prince of Wales in 1880. In 1878 he 

 received a letter from Lord Beaconsfield, announcing 

 that the Queen had been pleased to grant him a 

 pension of ;{^200 per annum. This recognition by his 

 country of his life of scientific labour was a subject of 

 much gratification to Mr. Joule. 



Special reference may be made to his connection with 

 the Literary and Philosophical Society of Manchester. 

 This commencing, as it practically did, at the age of fif- 

 teen, when he studied chemistry under Dalton in ths 

 rooms of the Society, continuing, by the most regular 

 attendance at all the meetings, so long as his health per- 

 mitted, and practically terminating with his death, must 

 have been one of the most important circumstances of 

 his life. Elected a member in the year of his greatest 

 discoveries, 1842, he was Secretary in 1846, Vice-President 

 in 1850, which office he held till his death, except during 

 the ten years when he was President. He took the 

 greatest interest in the welfare of the Society, and secured 

 not only the veneration but love of all the members. 



A man of science who left so deep a mark on his age 

 ought to have been buried in Westminster Abbey, but 

 unfortunately the necessary application could not be made, 

 in consequence of the delay in the public announcement 

 of his death. Prof. Osborne Reynolds, President of the 

 Manchester Literary and Philosophical Society, has 

 written to the Times urging that a monument should be 

 erected in the Abbey, and that steps should immediately 

 be taken to obtain, if possible, the consent of the Dean. 

 This suggestion ought to meet with cordial and unanimous 

 approval. Joule's name is one of which Englishmen may 

 justly be proud, and the erection of a monument in West- 

 minster Abbey would be the most fitting way in which 

 they could express their appreciation of the splendour of 

 his contributions to science. 



I Man. Lit. and Phil. Soc. , 1841-43 ; 

 "^ Phil. Mag., ser. 3, vol. xxiii. 



Phil. Mag., ser. 3, vjl. xix. p. 200. 



THE LIFE OF SIR WILLIAM ROWAN 



HAMILTON. 



Life of Sir William Rowan Hamilton. By Robert 



Percival Graves, M. A. Vol. III. "Dublin Universiti 



Press Series." (Dublin : Hodges, Figgis, and Co| 



1889.) 



AT last the third and final volume of Graves's lif 

 of Sir William Rowan Hamilton has seen tt 

 light. It was our pleasure in former numbers of NaturI 

 (vols, xxviii. p. I, and xxxii. p. 619) to have reviewed the 

 two earlier volumes, and we have now to congratulate the 

 University of Dublin on the completion of an adequate 

 biography of the most illustrious student that has eve 

 issued from its halls. This present volume, of which 

 are now to speak, is as portly as its predecessors, 

 contains not less than 673 pages, and a very importai 



