1813. ^ET. 60.] COUNT RUMFORD, 107 



* Advantages of Broad Wheels to Carriages ' is well known. 

 He put this in practice in his own chariot; but, though 

 there could be no doubt of their advantages, they were not 

 used by others, the Count's being the only carriage in Paris 

 that had them. Nor did anyone follow (which is not to 

 be wondered at) his whimsical winter dress, which was 

 entirely white, even his hat. This he adopted agreeably to 

 the law of nature, that more heated rays are thrown from a 

 dark body than from a light one. I do not know whether 

 his very simple, and I may add perfect, calorimeter is 

 known in England. The apparatus with which he was 

 making a series of experiments on the relative conducting 

 powers of different solid bodies for heat, and which death 

 prevented his completing, is of the greatest beauty. It 

 consists of a cylindrical vessel of cork (which is a perfect 

 non-conductor of heat), in the centre of the bottom of which 

 the small solid cylinder of the substance to be experimented 

 upon is fitted into an aperture of exactly the same diameter 

 as the cylindrical vessel, which is then filled with water, 

 and heat from the flame of a spirit-lamp is applied to the 

 lower extremity of the substance ; the time the heat takes 

 to pass through and raise the temperature of the water 

 indicates the relative conducting powers of the different 

 substances through which it is made to pass. He has 

 repeatedly declared to me it was his decided opinion that 

 heat and light were the result of vibrations in bodies, and 

 were not bodies themselves. He had lately brought to 

 the greatest perfection a lamp for burning spirits of wine, 

 and by which all explosion was rendered impossible. This 

 in France is of the greatest convenience, where, from the 

 low price of alcohol, it is nearly as economical as any other 

 fuel for heating water. 



The Count met with considerable plague in his pursuits 

 from the malignant disposition and jealousies of his fellow- 

 members of the National Institute, in consequence of having 

 differed in opinion on capillary attraction from their despotic 



