CHAP. VI., 4.] 



HEAT. RUMFORD HOPE. 



143 



well as to the material wealth of many districts, we 

 are disposed to give Rumford a higher place than has 

 generally been accorded to him. Had his excellent 

 principles been universally carried out, some millions 

 sterling would have been saved to every large state 

 in Europe. Fontenelle characteristically says of a 

 certain savant, who made experiments on nutrition, 

 with a view to carry fasting to the utmost practicable 

 extent, that his researches had the double aim of 

 a place in heaven and in the academy. Cuvier, who 

 tells the anecdote in his Eloye of Rumford, adds, 

 that the latter had a truer claim to the questionable 

 compliment. That science is surely not despicable 

 by which a pound of wool, of fuel, or of food, can be 

 made to go one-half farther than before in warming 

 the naked and in feeding the hungry. 



All Rumford' s experiments were made with admir- 

 eri- a ble precision, and recorded with elaborate fidelity, 

 nts. and in the plainest language. Everything with him 

 was reduced to weight and measure, and no pains 

 were spared to attain the best results. His experi- 

 ments on heat, and the properties of bodies in con- 

 nection with it, are the most important. He first 

 applied steam generally in warming fluids and to the 

 culinary art. He maintained the paradox of the 

 non-conducting power of liquids, which, though prac- 

 tically true, appears not to be rigorously so. He 

 contrived many ingenious instruments ; but his ther- 

 moscope, identical with Leslie's differential thermo- 

 meter, was probably of later invention, if not in 

 some measure borrowed from it. In like manner his 

 proofs of the maximum density point of water were 

 unquestionably suggested by Dr Hope's beautiful ex- 

 periment, although this derives its meaning from the 

 laws of convection, which Rumford first established. 

 636.) That water expands in bulk below the temperature 

 Hope on o f 39 or 40 Fahr. until it freezes, is a fact which 



had been asserted since the middle of the seventeenth 

 tn Q6n- 



point century. But for 150 years its great improbability, 

 vater. and the unquestionable uncertainty introduced into 

 the result by the irregular expansion of the contain- 

 ing vessel or glass of the thermometer, enabled scep- 

 tics in every generation to withhold their assent. Per- 

 haps the last who doubted was the illustrious Dalton. 

 He allowed himself however to be convinced by Dr 

 Hope's experiment, in which the temperature of the 

 denser and rarer water is measured by two thermo- 

 meters placed at the bottom and top of a cylindrical 

 jar, and nothing interferes with the natural tendency 

 of a fluid to arrange its particles according to their 

 specific gravity, the lighter resting on the heavier 

 ones. It is to be regretted that Hope did not pro- 

 secute original enquiry, for which the conception of 

 this experiment, and the mode in which he conducted 



it, 1 show that he had excellent qualifications. Hope 

 was first the colleague, then the successor of Black 

 in the chair of chemistry in Edinburgh ; and in his 

 time probably the most popular teacher in Europe 

 of that science. He died on the 13th June 1844, 

 in the seventy-eighth year of his age. 



Rumford's name will be ever connected with the (637.) 

 progress of science in England by two circumstances ; Ru _ mford 

 first, by the foundation of a perpetual medal and RoyaTli- 6 

 prize, in the gift of the Council of the Royal Society stitution. 

 of London, for the reward of discoveries connected 

 with Heat and Light ; and secondly, by the estab- 

 lishment, in 1800, of the Royal Institution in Lon- 

 don, destined, primarily, for the promotion of original 

 discovery, and, secondarily, for the diffusion of a taste 

 for science amongst the educated classes. The plan 

 was conceived with the sagacity which characterized 

 Rumford, and its success has been greater than could 

 have been anticipated. Davy was there brought into 

 notice by Rumford himself, and furnished with the 

 means of prosecuting his admirable experiments. 

 He and Mr Faraday have given to that institution 

 its just celebrity with little intermission for half a 

 century. 



Rumford spent his later years in Paris, where he (638.) 

 died in 1814. The estimation in which he was then Rumford's 

 held may be judged of from the fact, that he was 

 one of the eight foreign associates of the Academy 

 of Sciences. He was very capable of having done 

 more for science : the versatility of his talents, the 

 accidents of his early life, and the strong hold which 

 principles of philanthropy and public utility always 

 exerted over him, account for the absence of more 

 sustained and erudite researches. But in those very 

 particulars he deserves to be cited as a practical phi- 

 losopher, as to many things in advance of his age, 

 and a benefactor both to science and to mankind. 2 



In the history of pure science Rumford will be (639.) 

 chiefly remembered by his espousing the (not new) H . 19 ''P 1 ' 

 theory that heat consists in a motion of some kind tne nature 

 amongst the particles of matter, in opposition to the of heat im- 

 opinions then so prevalent amongst chemists, which portant. 

 almost tended to regard it as an element capable of 

 forming combinations. Rumford's view was mainly Derived 

 based on the facts of friction, which he showed to be f n ex P e " 

 irreconcilable with the notion of a change in the spe- f r j ct i on . 

 cific heat of the abraded matter, and to be seemingly 

 inexhaustible so long as the force producing friction 

 is continued. His conclusion was, that the heat 

 then generated cannot be a substance, but an affec- 

 tion of body of the nature of vibratory motion. The 

 amount of heat evolved in boring cannon is very 



1 Edinburgh Transactions, vol. v. 



2 Ilumford married (for the second time) Lavoisier's widow ; his daughter (by his first marriage) became Madame Cuvier. 

 Hence Cuvier's Eloge of Rumford contains the most authentic particulars of his life. Madame Ilumford survived until a few 

 years since, residing at Paris, where she formed a link between the savans of the age of Lavoisier, and those of the middle 

 of the nineteenth century. 



