266 



ENGINE TESTS. 



can best be studied by comparing the cylinder condensation and 

 leakage, in the case of the engines using superheated steam, 

 with the curve of condensation and leakage given on the chart 

 for simple engines using ordinary steam. For example, in the 

 case of test No. 1 C the cut-off is .392, the proportion of feed- 

 water accounted for at cut-off .947, and the cylinder conden- 

 sation and leakage 5.3%. On the curve for ordinary steam 

 referred to, the condensation and leakage at a cut-off of .392 

 is 16.7%. The difference between 5.3 and 16.7, which is 

 11.4%, represents the reduction in the condensation due to 

 the superheating, as determined by this method of comparison. 

 Pursuing the matter in the same way for the remaining 

 engines, we have the following table : 



From this comparison it appears that with steam superheated 

 41 (generally at a point near the boilers, and a considerable 

 distance from the engine), the proportion of condensation and 

 leakage was reduced an average of 8.7%. Assuming as a 

 criterion the relation between the actual saving in the case of 

 No. 1 Engine, and the reduced proportion of cylinder condensa- 

 tion, which was about .8, this reduction in the cylinder con- 

 densation corresponds to an actual saving of feed- water of 7%. 

 Assuming that if the engines had been supplied with ordinary 



