146 COUNT RTJMFOKD. 



he wrote it, have been acquainted with the experiments 

 and the reasonings of Boyle and Hooke, of Leibnitz 

 and Locke. As regards the nature of heat, these men 

 were quite as far removed from metaphysical subtleties 

 as Eumford himself. They regarded heat as ' a very 

 brisk agitation of the insensible parts of an object 

 which produces in us that sensation from whence we 

 denominate the object hot; so what in our sensation 

 is heat, in the object is nothing but motion.' Locke, 

 from whom I here quote, and who merely expresses 

 the ideas previously enunciated by Boyle and Hooke, 

 gives his reasons for holding this theoretic conception^ 

 ' This,' he says, ' appears by the way heat is produced, 

 for we see that the rubbing of a brass nail upon a 

 board will make it very hot ; and the axle-trees of carts 

 and coaches are often hot, and sometimes to a degree 

 that it sets them on fire, by the rubbing of the naves 

 of the wheels upon them. On the other side, the ut- 

 most degree of cold is the cessation of that motion of 

 the insensible particles which to our touch is heat.' 

 The precision of this statement could not, within its 

 limits, be exceeded at the present day. 



There is a curious resemblance, moreover, between 

 one of the experiments of Boyle, and the most cele- 

 brated experiment of Rumford. Boyle employed three 

 men, accustomed to the work, to hammer nimbly a 

 piece of iron. They made the metal so hot, that it 

 could not be safely touched. As in the case of Rum- 

 ford, people were looking on at this experiment, and 

 Boyle's people, like those of Rumford, were struck 

 with wonder, to see the sulphur of gunpowder ignited 

 by heat produced without any fire. Hooke is equally 

 clear as regards the nature of heat, and like Rumford 

 himself, but more than a century before him, he com- 

 pares the vibrations of heat with sonorous vibrations. 



