86 Hough — Mechanical Equivalent of the 



would be enhanced in value. Hence an absolute determina- 

 tion of the mechanical equivalent of the heat of vaporization 

 of water is a thing to be desired in itself. 



The present method aims at the elimination of the errors 

 due to thermometry, the calorimeter constant, the water vapor 

 in the steam, radiation and convection, and a rigorous correc- 



tion for conduction. The devices used to attain these ends 

 will be described in detail followed by a discussion of the prin- 

 ciples involved. 



The general plan of the machine and the relation of its parts 

 is best shown by the photograph (iig. 1) and the conventional 

 diagrams (tigs. 2 and 3). It consists essentially of (a) a vertical 



