158 THE CANADIAN NATURALIST. [April 



' One horse would have been equal to the work performed, 

 though two were actually employed. Heat may thus be produced 

 merely by the strength of a horse, and in a case of necessity this 

 might be used in cooking victuals. But no circumstances could 

 be imagined in which this method of producing heat could be 

 advantageous, for more heat might be obtained by using the fodder 

 necessary for the support of the horse, as fuel. 



' By meditating on the results of all these experiments, we are 

 naturally brought to that great question which has so often been 

 the subject of speculation among philosophers, namely, What is 

 heat ? Is there such a thing as an igneous fluid ? Is there any- 

 thing that with propriety can be called caloric ? 



' We have seen that a very considerable quantity of heat may 

 be excited by the friction of two metallic surfaces, and given off in 

 a constant stream or flux in all directions, without interruption or 

 intermission, and without any signs of diminution or exhaustion. 

 In reasoning on this subject we must not forget that most remark- 

 able circumstance, that the source of the heat generated by friction 

 in these experiments appeared evidently to be inexhaustible. [The 

 italics are Rumford's.] It is hardly necessary to add, that any- 

 thing which any insulated body or system of bodies can continue 

 to furnish without limitation, cannot possibly be a material sub- 

 stance; and it appears to me to be extremely difficult, if not quite 

 impossible, to form any distinct idea of anything capable of being 

 excited and communicated in those experiments, except it be 



MOTION.' 



" No one can read the remarkably able and lucid paper from 

 which these extracts are taken, without being struck with the per- 

 fect distinctness with which the problem to be solved was pre- 

 sented, and the systematic and conclusive method of its treatment. 

 Rumford kept strictly within the limits of legitimate inquiry, 

 which no man can define better than he did. ( I am very far 

 from pretending to know how, or by what means or mechanical 

 contrivances, that particular kind of motion in bodies, which has 

 been supposed to constitute heat, is exerted, continued, and pro- 

 pagated, and I shall not presume to trouble the Society with new 

 conjectures. But although the mechanism of heat should in part 

 be one of those mysteries of nature which are beyond the reach of 

 human intelligence, this ought by no means to discourage us, or 

 even lessen our ardor in our attempts to investigate the laws of its 

 operations. How far can we advance in any of the paths which 



