Il6 REGNAULT'S RESEARCHES. 



On April 26, " Memoir es de F Academie des Sciences, ae 

 Elnstitut de France, Tome XXI." was published, and con- 

 tained " Relation des Experiences Enterprises par Ordre de 

 Monsieur le Ministre des Travaux Publiqties et sur la 

 proposition de la Commission Centrale des Machines a 

 Vapeur, Pour Determiner les principales Lois et les Donriees 

 Numeriques qui entrent Dans le Calcul des Machines a 

 Vapeur par M. V. Regnault!' 



The publication of the first ten Memoirs of Regnault's 

 now classical researches, containing full and accurate 

 experimental determinations of the numerical relations 

 between volume, density, pressure, and temperature of air, 

 and particularly the relation between the temperature,, 

 pressure, and latent heat of steam, unquestionably took an 

 important, if not a first, place in the sudden interest which 

 arose in the theory of heat engines. 



Sir William Thomson, at the time his attention was 

 caught by Joule's discovery of the heat produced by the 

 friction of water, had already published some 26 papers on 

 theoretical physics, notwithstanding that he had only taken 

 his degree two years before. These papers were largely 

 devoted to the theory of the conduction of heat ; but 

 although at the time he was not only acquainted with 

 Carnot's theory, but firmly convinced of its truth, he had 

 not touched in any of his papers on the subject of the 

 production of mechanical effect by thermal means, nor does 

 he touch upon this in the first ten papers which he pub- 

 lished during the succeeding eight months ; but in June, 

 1848, he read a paper at the Cambridge Philosophical 

 Society, " On an Absolute Thermometric Scale founded on 

 Carnot's Theory of the Motive Power of Heat, and calcu- 

 lated from Regnault's observations." 



