A HISTORY OF SCIENCE 



machinery being kept immersed in water, the access 

 of the air of the atmosphere was completely prevented. 



"Was it furnished by the water which surrounded 

 the machinery? That this could not have been the 

 case is evident : first, because this water was continually 

 receiving heat from the machinery, and could not, at 

 the same time, be giving to and receiving heat from the 

 same body ; and, secondly, because there was no chem- 

 ical decomposition of any part of this water. Had any 

 such decomposition taken place (which, indeed, could 

 not reasonably have been expected), one of its compo- 

 nent elastic fluids (most probably hydrogen) must, at 

 the same time, have been set at liberty, and, in making 

 its escape into the atmosphere, would have been de- 

 tected; but, though I frequently examined the water 

 to see if any air-bubbles rose up through it, and had 

 even made preparations for catching them if they 

 should appear, I could perceive none; nor was there 

 any sign of decomposition of any kind whatever, or 

 other chemical process, going on in the water. 



"Is it possible that the heat could have been sup- 

 plied by means of the iron bar to the end of which the 

 blunt steel borer was fixed ? Or by the small neck of 

 gun-metal by which the hollow cylinder was united to 

 the cannon? These suppositions seem more improb- 

 able even than either of the before-mentioned ; for heat 

 was continually going off, or out of the machinery, by 

 both these passages during the whole time the experi- 

 ment lasted. 



"And in reasoning on this subject we must not for- 

 get to consider that most remarkable circumstance, 

 that the source of the heat generated by friction in 



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