MR. TYNDALL GIVES NO SOLUTION. 79 



before unknown, the love of systematic order and har- 

 mony, which is implanted in every mind." 



The result of his interesting inquiry is the final 

 conclusion, that " heat is a mode of motion," a 

 conclusion anticipated by Bacon more than two 

 hundred and fifty years ago; who said, that "all 

 knowledge of heat is limited to ideas of a peculiar 

 mode of motion, produced by some unexplained 

 cause." Others have considered the reciprocal 

 divergency of particles by absorption of heat (de- 

 noted expansion), to be somewhat analogous to 

 the swelling of a sponge by the absorption of 

 water. 



As to what moves, or is put in motion, or is the 

 cause of the motion which develops the phenom- 

 enon of heat, Mr. Tyndall gives no solution : he 

 leaves it, as Bacon left it, an " unexplained cause." 



To illustrate how heat is produced by motion, 

 Mr. Tyndall and other chemists refer to the mo- 

 tion of a hammer in pounding a piece of lead, or 

 iron on an anvil ; whereby the metal is speedily 

 rendered hot. 



Mr. Tyndall affirms : 



" The dynamic power of heat is due to what is called 

 chemical affinity, which is a pure attraction of the same 

 mechanical quality as gravity ; causing every oxygen 

 atom, in the process of the combustion of a diamond in 

 oxygen gas, to strike against its surface, and to transfer 

 its motion, by collision, into the mode of motion we call 

 heat. 



