Manchester Memoirs, Vol. Ixv. (1921), No. 2 11 



the case of the Uniflow engine, the working fluid is practically 

 always superheated steam, and it would appear from the 

 agreement between the curves of Fig. 7 and Fig. 3 that 

 formula (6), with suitable values for the constants inserted 

 therein, could be applied to this engine and used as a standard 

 of comparison. The equations deduced by Stumpf are much 

 more elaborate and involved (as is usual for efficiency expres- 

 sions of cycles in which steam is the working fluid) and 

 further require the use of an entropy diagram to determine 

 the efficiency values in each case. Comparing the chain lines 

 of Figs. 3 and 7, the agreement is obvious. It should be 

 observed, of course, that the curves of Fig. 2 give steam con- 

 sumption values against percentage compression, so that the 

 minimum steam consumption values of that figure correspond 

 to the maximum efficiency values of Fig. 3. 



The originators of the Uniflow engine appear to have been 

 to some degree inspired by the Mechanical principle involved 

 in the operation of a well-known internal combustion engine 

 known as the Koerting gas engine. Perhaps the Uniflow 

 engine in its turn may be the means of drawing the attention 

 of internal combustion engineers to a Thermodynamical prin- 

 ciple which offers a chance of improving upon Diesel engine 

 efficiencies. 



