182 DISCOVERY OH. 



himself to the elaboration of methods of working, 

 modifying and repeating experiments in various ways 

 in order to determine its numerical value with increased 

 exactness. Many investigators have followed him 

 along the same roads, arriving at much the same value 

 as he did ; and the generalisation thus established 

 upon unimpeachable evidence is embodied in the First 

 Law of Thermodynamics, familiar to every mechanical 

 engineer as well as to all physicists, and expressed in 

 the words, " When work is transformed into heat, or 

 heat into work, the quantity of work is mechanically 

 equivalent to the quantity of heat." " Joule's initial 

 work," said Lord Kelvin, when unveiling a statue of 

 him at Manchester in 1893, " was the very foundation 

 of our knowledge of the steam engine and steam power. 

 Taken along with Carnot's work it gave the scientific 

 foundation on which all the great improvements since 

 the year 1850 had been worked out, not in a haphazard 

 way, but on a careful philosophical basis." 



Joule's work stands in the esteem of men of science 

 by the side of that of Newton, yet when a movement 

 was started to commemorate it in Westminster Abbey, 

 the Dean of Westminster had to confess he was un- 

 acquainted with it, and only after some difficulty was 

 an area about two feet square in a dark corner placed 

 at the disposal of the memorial committee in the 

 English Valhalla. 



" And so," says Sir Henry Roscoe, in describing the circum- 

 stances which led to the memorial, " a simple tablet is inserted 

 in one of the side walls just below the effigy of Charles Darwin ; 

 and thus within a foot or two of one another are placed the 

 simple and unattractive acknowledgments of work done, the 

 like of which hath not been seen, and the importance of which 

 cannot be reckoned. The ridiculous, if it were not the pathetic, 

 position thus accorded to two men who have conferred inestimable 



