238 THE POPULAR SCIENCE MONTHLY. 



celebrated French chemist Lavoisier, who was beheaded in the French 

 Revolution. The union, however, not proving a happy one, they soon 

 separated, and Rumford died in his residence at Auteuil the 21st of 

 August, 1814. His first wife had died in 1792, and his daughter, who 

 inherited his title, had come to him at Munich, and returned to Amer- 

 ica after her father's decease. 



The philanthropic interest of Count Rumford in the poor and de- 

 fective domestic life of the lower classes of society had a gi'eat influ- 

 ence in determining the course of his scientific inquiries. It was this 

 feeling that led him to investigate the properties and domestic man- 

 agement of heat. He determined the amount of it arising from the 

 combustion of different kinds of fuel, by means of a calorimeter of his 

 own invention. He reconstructed the fireplace, and so improved the 

 methods of warming apartments and cooking food as to produce a 

 saving of from one-half to seven-eighths of the fuel previously con- 

 sumed. He improved the construction of stoves, cooking-ranges, coal- 

 grates, and chimneys, and showed that the non-conducting power of 

 cloth is due to the air inclosed among its fibres ; and he first pointed 

 out that mode of action of heat called convection; indeed, he was the 

 first clearly to discriminate between the three modes of propagation 

 of heat radiation, conduction, and convection. He determined the 

 almost non-conducting properties of liquids, investigated the sources 

 of the production of light, and invented a mode of measuring it. He 

 was the first to apply steam generally to the warming of fluids and to 

 culinary operations. He also, as has been stated, experimented ex- 

 tensively upon the use of gunpowder, the strength of materials, and 

 the maximum density of water, and made many valuable and original 

 observations upon an extensive range of subjects, which are described 

 in the essays recently for the first time published in a complete form. 

 As Prof. J. D. Forbes remarks, " all Rumford's experiments were made 

 with admirable precision, and recorded with elaborate fidelity and in 

 the plainest language. Everything with him was reduced to weight 

 and measure, and no pains were spared to obtain the best results." 



But it was his investigations concerning the nature of heat that 

 will make him immortal. By experiments in boring cannon he proved 

 its immateriality, and that it does not consist of an imponderable sub- 

 stance or fluid, as implied by the old theory of caloric. In these ex- 

 periments he demonstrated that the heat generated by friction does 

 not come from any latent source in the materials used, but is derived 

 from the power spent in producing the friction ; that its amount is in 

 the ratio of the power expended ; that it is a case of the transforma- 

 tion of energy, and a mode of molecular motion. He was half a cen- 

 tury in advance of his age, and his researches were long unappre- 

 ciated ; but they are now recognized as forming an epoch in the 

 progress of physical science. 



