REVIEW OF FEED-WATER TESTS. 



255 



fairly compared for this purpose are those numbered 32, 34, 36, 

 49, 53, 55, 56, and 58A. The range of cut-off in the high- 

 pressure cylinder is from .238 to .331, and the range of steam 

 accounted for at cut-off in the same cylinder is from .717 to 

 .866. These are tabulated below : 



The average cylinder condensation and leakage in these 

 cases is 100-79.3 = 20.7%, and the average cut-off in the high- 

 pressure cylinder is .303. If these be compared with the 

 curve of condensation and leakage given on the chart for the 

 simple engines, it will be seen that this average falls closely 

 upon that curve. The point on the curve for 30% cut-off is 

 20.5%. The engines selected are those in which the high-pres- 

 sure cylinder is unjacketed, or of the class in which the jacket 

 space forms a thoroughfare through which steam is supplied 

 to the chest. It may be inferred from the close agreement be- 

 tween the average of these tests and the indications of simple 

 engines in the matter, that the curve of condensation and leak- 

 age for simple engines applies also to the high-pressure cylinder 

 of compound engines where these are unjacketed, and where 

 the valves and pistons are fairly tight. 



( nndensation and leakage in the low-pressure cylinder of the 

 compound engines reported above is affected to a considerable 

 extent by the conditions regarding jacketing and reheating, 

 Where there is neither jacketing nor reheating, the conden- 



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