Proceedings of the Roi/al Society. 383 



sopher, are constantly leadini^ to new discoveries : and not- 

 withstanding the important labours of Arago, Biot, Brewster, 

 and Herschel, the inquiry is not yet exhausted ; and it is ex- 

 tremely probable that these beautiful results will lead to a more 

 profound knowledge than has hitherto been obtained concerning 

 the intimate constitution of bodies, and establish a new con" 

 nexion between mechanical and chemical philosophy. 



" The subject of heat, so nearly allied to that of light, has 

 lately afforded a rich harvest of discovery, yet it is fertile in un- 

 explored pheenomena. The question of the materiality of heat 

 will probably be solved at the same time as that of the undu- 

 latory hypothesis of light, should the human mind ever be capa- 

 ble of understanding the causes of these mysterious phaenomena. 

 The applications of the doctrines of heat to the atomic or cor- 

 puscular philosophy of chemistry, abound in new views ; and 

 probably at no very distant period these views will attain a pre- 

 cise mathematical form. There are many remarkable circum- 

 stances which seem to point to some general law on the subject. 

 First, — the apparent equable motion of radiant matter, or light 

 and heat, through space : — 2, The equable expansion of all 

 elastic fluids by equal increments of temperature : — 3, The 

 contraction or expansion of gases by chemical changes, in some 

 direct ratio to their original volume ; for instance, ^ov \ : — 4, 

 The circumstance that the elementary particles of all bodies 

 appear to possess the same quantity of heat. 



" In electricity the wonderful instrument of Volta has done 

 more for the obscure parts of physics and chemistry, than the 

 microscope ever effected for natural history, or even the teles- 

 cope for astronomy. After presenting to us the most extraordi- 

 nary and unexpected results in chemical analysis, it is now 

 throwing a new light upon magnetism : 



" M agnos accinctus in usus." 



But upon this question I shall enter no farther, as it has been 

 discussed in the discourse given in the award of the Copleian 

 medal to M. Oersted, by my predecessor in office, with all his 

 peculiar sagacity and happy talent of illustration. 



