lo Wilson and Noble, Entropy Diagrams. 



engines could be traced, and the various losses definitely 

 analysed. 



Fig. 3 is an example of the mean diagrams from a 

 Triple Expansion Engine trial compounded in this 

 manner, the low-pressure diagram being uncompleted for 

 reasons of economy of space. The dotted line shews the 

 diagrams before setting back with the clearance expansion 

 lines in position. Diagrams such as Fig. III. can be con- 

 verted into entropy diagrams by the graphical method 

 introduced by Professor Boulvin.* 



Fig. 4 is such a diagram from the mean cards of a 

 set of diagrams taken from the engines of the steamship 

 " Tartar," the trials of which were described in the Pro- 

 ceedings of the Institution of Mechanical E?tgineers for 

 1890 and 1894. It will be noticed that the expansion 

 lines of the diagrams by this method are roughly in coin- 

 cidence with the adiabatic expansion line, thus shewing 

 that the jackets were doing little more than preventing 

 the conduction of heat away from the cylinders. Con- 

 sidering the small ratio the jacket water bore to the 

 cylinder feed (3"94%), this is only what might have been 

 expected. 



The position of the expansion line with regard to the 

 adiabatic line also seems to corroborate the assumption, 

 which was generally made, in the discussion of this trial, 

 to explain the magnitude of the missing steam, viz., that 

 there had been a large amount of priming. For, had 

 initial condensation been the only factor, the expansion 

 line ought to have left the adiabatic as the temperature 

 fell, on account of the heat regained from the walls of the 

 cylinder. 



Constant volume curves have been drawn in for the 

 5team during expansion after release. In the low pressure 



* Engineering, 1 896. 



