354 On the PROGRESS of HEAT 



""fented as the grand excellence of the Huttonian Theory *." 

 " Again, he obferves, in giving what he fays appears to him a 

 demonftration of the fallacy of the firfl principles of the Hut- 

 tonian Syftem, " it will not be difputed, that the tendency of 

 " caloric is to dimife itfelf over matter, till a common tempe- 

 " rature is eftablifhed. Nor will it probably be denied, that a 

 u power conftantly difTufing itfelf from the centre of any mafs 

 " of matter, cannot remain for an indefinite time locally accu- 

 " mulated in that mafs, but mull at length become equal or 

 " nearly fo over the whole f .'* 



2. 1 mufl confefs, notwithstanding the refpect I entertain for 

 the acutenefs and accuracy of the author of this reafoning, that 

 it does not appear to me to pofTefs the force which he afcribes to 

 it ', nor to be confiftent with many facts that fall every day un- 

 der our obfervation. A fire foon heats a room to a certain de- 

 gree, and though kept up ever fo long, if its intenfity, and all 

 other circumftances remain the fame, the heat continues very 

 unequally diftributed through the room ; but the temperature 

 of every part continues invariable. If a bar of iron has one 

 end of it thruft into the fire, the other end will not in any 

 length' of time become red-hot ; but the whole bar will quick- 

 ly come into fuch a ftate, that every point will have a fixed 

 temperature, lower as it is farther from the fire, but remain- 

 ing invariable while the condition of the fire, and of the 

 medium that furrounds the bar, continues the fame. The 

 reafon indeed is plain : the equilibrium of heat is not fo much 

 a primary law in the diftribution of that fluid, as the limitation 

 of another law which is general and ultimate, confifling in the 

 tendency of heat to pafs with a greater or a lefs velocity, 

 according to circumftances, from bodies where the temperature 



is 



* Murray's Syjlem of Chtrni.tfry, vol. iii. Appendix, p. 49. 

 t Page 51. 



