142 



MATHEMATICAL AND PHYSICAL SCIENCE. 



[Diss. VI. 



sidering the novelty of the experiment in 1804 (only 

 twenty-one years after Montgolfier's first successful 

 experiment), this fact speaks strongly for his courage 

 and zeal. These ascents were also the first undertaken 

 with strictly scientific aims, and the observations made 

 were highly interesting in connection with the decre- 

 ment of temperature in the atmosphere, with the uni- 

 formity of composition of air at all heights, and with 

 the question of whether the magnetic force of the 

 earth diminishes at such elevations. This last en- 

 quiry was not conclusively answered. 

 (631.) With M. de Humboldt he made observations on 



terrestrial magnetism in Italy, and on other subjects. Miscella- 

 By desire of Laplace he studied the facts of capillary neous ex- 

 attraction. In more immediate connection with the P e " ment 

 subject of the present chapter, he made some valu- Lussac* 

 able experiments on hygrometry, on the mechanical 

 properties of vapour of different kinds, and on the 

 specific heat of the gases. His fame, however, mainly 

 rests on the two investigations to which we previously 

 referred, and on the results of his balloon journey. 

 His later years were devoted to practical enquiries 

 connected with chemistry, and to his official duties at 

 the Mint. He died at Paris on the 9th May 1850. His death. 



4. RUMFORD. Economical applications of Heat. Point of Maximum Density of Water; Hope. 

 Friction as a source of Heat. Theory that Heat is convertible into Mechanical Energy ; 

 Mr Joule. 



(632.) 

 Thomson, 

 Count of 

 Rumford. 



(633.) 

 His early 

 history 

 and studies 



(634.) 

 Enquiries 

 into the 

 economical 

 applica- 

 tions of 

 heat. 



THE name of Thomson, Count of Rumford, de- 

 serves a passing notice in the history of the physi- 

 cal sciences, if not for the absolute importance of 

 his discoveries, at least as an instance of a class of 

 benefactors to mankind at once in a physical and in- 

 tellectual point of view. He was altogether in ad- 

 vance of his age in the application of correct theory 

 to the improvement of the social condition of the 

 lowest classes ; and many of his experiments, and, 

 indeed, discoveries, seem now at once so simple and 

 so familiar, that we are apt to forget how entirely 

 original they were sixty years since. 



Sir BENJAMIN THOMSON, an American by birth, a 

 British knight, and a Bavarian or rather Austrian 

 count, was born in the United States in 1753, and 

 passed his earlier years almost entirely at military 

 stations during the American war, being engaged 

 on the British side. After the establishment of in- 

 dependence, he quitted his country for ever ; came 

 first to England, where he was well received, and 

 proposing to enter the Austrian service, he proceeded 

 as far as Munich, where, having become known to 

 the elector of Bavaria, he was induced to settle ; 

 and having received different civil and military ap- 

 pointments, he devoted himself for a series of years 

 to the improvement of the social condition of that 

 capital. He introduced great improvements into the 

 management of the army; the mechanical and chemi- 

 cal departments of the artillery had a peculiar charm 

 for him ; they were conducted on strictly scientific 

 principles, and, in return, were made to contribute 

 important results to science. His experiments on the 

 heat of friction, deduced from the boring of cannon, 

 are amongst the best we possess ; and they led him 

 to results of considerable theoretical importance to 

 which I shall presently refer. 



But his most serviceable efforts on behalf of man- 

 kind were in the treatment of the mendicant classes 



with which Munich then swarmed. Salutary views 

 of the importance of industry, order, morality, and 

 public economy, were most happily united to a 

 happy versatility of talent in physical research, to 

 unwearied patience and great liberality, in effecting 

 one of the greatest social reforms rf>n record. The 

 strict statistics of a great house of industry were 

 ascertained with reference to the most seemingly in- 

 significant details, and, in particular, all the appli- 

 cations of Heat to the physical wants of mankind 

 were studied with equal assiduity and success. The 

 wdrmch of clothing was traced to the amount of still 

 air entangled amongst its fibres, the dissipation of 

 heat, whether from a thermometer or a kitchen boiler, 

 was classified under radiation, conduction, and con- 

 vection, the last and often most important of which 

 (signifying the influence of currents in liquids and 

 gases in conveying heat by the changing density of 

 their parts) had hardly before been recognised, or at 

 least made the subject of formal experiment, the 

 effective heat due to the combustion of different kinds 

 of fuel, tested by a calorimeter of his own invention, 

 the economy of light based on an investigation of 

 the properties of flame ; these were but a few of 

 the trains of enquiry, of which his Mendicity House 

 was the primary object. Charity and science went Practical 

 hand in hand ; and when we award to Watt the benefits 

 highest honours for an invention which enabled him su 

 to create mechanical force at an economy of two- 

 thirds of the coal previously consumed, shall we 

 deny Rumford a civic crown for having so improved 

 the methods of heating apartments and of cooking 

 food, as to produce a saving in the precious element 

 of heat, varying from one-half to seven-eighths of the 

 fuel previously consumed ? x When we consider the 

 enormous price of wood in nearly every part of the 

 Continent, the destruction of forests which has oc- 

 curred, and the consequent injury to the climate, as 



1 In the hospital of Verona he reduced the consumption of wood to one-eighth. 

 would not rest until he had cooked his dinner with his neighbour's smoke. 



Some one wittily said of Rumford, that he 



