280 Mr. Rankine on the Transformation of Energy. 



manently transformed from tbe actual to the potential form, tbat is to 

 say, the work done by the engine will be — • 



The ratio of this work to the total expenditure of energy is 



H) — Hg Qg — Qg .„ s 



H, - Q: ^'-^ 



This principle is applicable to all possible engines, known and 

 unknown. 



In the sequel of the paper, tbe author gives some examples of tbe 

 application of the general principles of tbe transformation of energy to 

 tbe theory of heat, and to tbat of electro-magnetism ; and deduces from 

 them, as particular cases, several laws already known through specific 

 researches. 



The details of tbe application of these principles to the theory of beat 

 are contained in the sixth section of a memoir read to the Royal Society 

 of Edinburgh, "On the Mechanical Action of Heat." 



The actual energy produced by an electric pile in unity of time is 



expressed by — 



Q = Mu 



where M is the electro-motive force, and u, tbe strength of the current. 

 Tbe actual energy of an electric circuit is expressed by — 



Ru2 



wbere R is the resistance of the circuit. This energy is immediately 

 and totally transformed into sensible heat. 



Tbe proportion of the actual energy produced in the pile which is 

 transformed into mechanical work by an electro-dynamic machine is 



represented by — 



Qi — Qg ^M — Ru 



Q2 M 



The strength of tbe cui-rent is known to be found by means of the 



equation — 



M — N 



"=-R- 



where N is the negative or inverse electro-motive force of tbe apparatus 

 by means of which electricity is transformed into mechanical work. 

 Hence 



Qi — Q2 N 

 Qi ~ M- 



The above particular' forms of the general equation, agree with formulae 

 already deduced from special researches by Mr. Joule and Professor 

 William Thomson. 



