252 



ENGINE TESTS. 



to leak, and then a comparison is made between the loss in the 

 tight engine and that in the leaking engine, an inference can be 

 drawn as to the extent of the leakage and how much the loss 

 amounts to in percentage of the whole consumption. Practi- 

 cally, it may be said that it is unnecessary to know the absolute 

 amount of cylinder condensation, for it is seldom that an engine 

 is found in an absolutely tight condition ; and, after all, the im- 

 portant thing to know is what the cylinder condensation and 

 leakage amount to when the engine is in ordinarily good work- 

 ing condition. These tests furnish satisfactory evidence on this 

 point, especially those made on simple engines. Selection may 

 properly be made from the list of simple engines, those of the 

 larger sizes of the four-valve type, using ordinary steam, taking 

 those which are tight or leaking only a small amount ; namely, 

 those numbered 1, 2, 3, 5, 6, 7, 17, 18, 20, 22, 25, 28, 29, 30, 

 and ol. These are tabulated as follows, being arranged in Un- 

 order of the point of cut-off : 



