CHAP. VI., 2.] 



HEAT. CAVENDISH. 



133 



(600.) 

 'apers on 

 ae earth's 

 ttraction, 

 n.d theory 

 f electri- 

 ity. 



(601.) 

 ingular 

 ersonal 

 haracter- 

 itics of Ca- 

 endish. 



truth. But it is needless to dwell upon these obser- 

 vations, however original, because they were volun- 

 tarily suppressed by the author, and have only re- 

 cently been brought to light from his manuscripts. 1 

 What he did publish in connection with this subject 

 was a paper on the construction and graduation of 

 meteorological instruments, especially thermometers, 

 and others on the temperature at which mercury 

 freezes, and on freezing mixtures. The former of 

 these papers was, as might be expected, far in ad- 

 vance of its age in the degree of exactness which was 

 shown to be attainable in the construction of ther- 

 mometers, and scarcely even now can it be considered 

 as obsolete. The papers on freezing mercury finally 

 corrected the exaggerated notion at first entertained 

 of the extreme cold at which that metal becomes 

 solid, and also contain valuable views on the sub- 

 ject of congelation, and fixed the latent heat of water 

 at 150. He calls this, " generation of heat" during 

 liquefaction, objecting to Black's term as relating 

 " to an hypothesis, depending on the supposition that 

 the heat of bodies is owing to their containing more 

 or less of a substance, called the matter of heat ; and 

 as I think Sir Isaac Newton's opinion that heat con- 

 sists in the internal motion of the particles of bodies 

 much the most probable, I chose to use the expres- 

 sion, heat is generated." 2 



Two of Cavendish's most important researches re- 

 fer to the attraction and density of the earth, and to the 

 mathematical theory of electricity. The former (which, 

 in principle, was derived from the Rev. John Michell) 

 has been already analyzed in the chapter on Astro- 

 nomy (art. 156). The latter will be more conve- 

 niently referred to in our chapter on Electricity. 



Cavendish's publications extended over the greater 

 part of his active life, but those on chemistry and 

 electricity, on which his fame principally depends, 

 do not extend beyond the year 1775 ; the date of his 

 paper on the density of the earth is 1798. He died 

 24th February 1810, at the age of 79. He appears 

 to have. exercised scarcely less influence by his general 

 devotion to science, than by his specific discoveries, 

 great and original as they were. In 1782, when 

 Playfair met him incidentally in London, he de- 

 scribed him as being generally looked up to as one 

 possessed of talents confessedly superior, and as the 

 only member of the Royal Society who then united 

 the knowledge of mathematics, chemistry, and ex- 

 perimental philosophy. The absolute devotion of 

 his life to inquiries the most abstractly scientific, 

 whilst he showed an entire indifference to the luxuries 

 which his wealth might have commanded, and the 

 social station to which his birth entitled him, could 

 not fail to inspire respect for his character, as well 

 as to obtain the homage of mankind for pursuits 

 so dignified and so generally disregarded. Many 



curious anecdotes are related of the annoyance which 

 the inevitable accumulation of his unspent income 

 occasioned. He no doubt would have distributed more 

 liberally what he so little valued, but for the amount 

 of time and inquiry which such a course must have 

 compelled him to withdraw from his beloved pursuits. 

 Some instances of his generosity are on record, and 

 others, no doubt, will never come to light. M. Biot's 

 epigrammatic description of him will probably long 

 remain applicable, " II etait le plus riche de tous 

 les savans, et probablement aussi le plus savant de 

 tous les riches." 



This isolation of interest was doubtless due, quite (602.) 

 as much to a constitutionally morbid temperament, 

 as to a real misanthropy. He avoided even the most 

 casual intercourse with his fellow men, excepting only 

 when it was likely to bear the immediate fruit of 

 scientific information. He almost never visited his 

 relatives, and his heir paid him a visit of a few minutes 

 once a year ; but he frequented regularly the social 

 meetings of the Royal Society Club, and the evening 

 reunions of Sir Joseph Banks. But he came, not to 

 participate, but to increase his stores ; if he spoke, it 

 seemed to be by inadvertence, and he was silenced 

 by a question, or even by a look. " A sense of iso- 

 lation from his brethren made him shrink from their 

 society, and avoid their presence ; but he did so as 

 one conscious of an infirmity, not boasting of an ex- 

 cellence. He was like a deaf-mute sitting apart from 

 a circle, whose looks and gestures show that they are 

 uttering and listening to music and eloquence in pro- 

 ducing or welcoming which he can be no sharer. . . . 

 He was one of the unthanked benefactors of his race 

 who was patiently teaching and serving mankind, 

 whilst they were shrinking from his coldness, or 

 mocking his peculiarities. . . . Such was he in life, 

 a wonderful piece of intellectual clock-work, and as he 

 lived by rule he died by it, predicting his death as if it 

 had been the eclipse of some great luminary, . . . and 

 counting the very moment when the shadow of the 

 unseen world should enshroud him in its darkness." 3 



I shall only add, that Cavendish was elected one 

 of the eight Associates of the French Institute in 

 1803. This is a distinction perhaps the highest, of 

 a formal kind, to which a scientific man can aspire, 

 and was given at a time when, as an Englishman, he 

 must have felt it to be peculiarly honourable. 



The philosophical character of Cavendish resembled . . . 

 in many respects that of Newton ; and with but a slight His philo- 

 modification of its secondary ingredients, he might sophical 

 have been, perhaps, another Newton in experimental character, 

 physics. His singular incommunicativeness, and the 

 absence of a laudable ambition to perpetuate his name 

 by the establishment of great theories, are perhaps 

 the main reasons why his reputation, except in che- 

 mistry, did not stand yet higher than we find it. 



1 By the Rev. W. Vernon Harcourt in British Association Report for 1839. 



2 Phil. Trans. 1783. 



3 Wilson's Life of Cavendish. 



Compare Wilson's Life of Cavendish, p. 446. 



