THE BEGINNINGS OF LIFE. 



that heat generates motion (though both are true in 

 certain cases), but that heat itself, its essence and 



quiddity, is motion and nothing else Heat is 



a motion, expansive, restrained, and acting in its strife 

 upon the smaller particles of bodies V Locke, also, 

 shortly afterwards, expressed himself in much the same 

 terms. He said: c Heat is a very brisk agitation 

 of the insensible parts of the object, which produces 

 in us that sensation from whence we denominate 

 the subject hot- so that what in our sensation is 

 heat^ in the object is nothing but motion? But it was 

 not till quite the close of the last century, in 1798, 

 that Benjamin Thompson, afterwards Count Rumford, 

 announced to the Royal Society his conviction, based 

 upon real experimental evidence, that heat was a 

 mode of motion. Whilst superintending the boring 

 of cannon in the military arsenal at Munich, Count 

 Rumford was much struck with the heat acquired by 

 the brass after it had been bored for a time, and 

 also with the intense heat of the metallic chips which 

 were separated by the borer 2 . He then instituted 

 the most careful experiments to ascertain the source 

 of this heat, and in his memoir, after having de- 

 tailed the nature and results of these experiments, he 

 made the following remarks in opposition to the then 

 prevalent notion that heat was a material substance, 

 a kind of igneous fluid named c caloric:' c We have 



1 Bacon's Works, vol. iv. Spedding's Translation. 



2 See Tyndall's ' Heat Considered as a Mode of Motion,' 1863, p. 53. 



