ENGINE No. 40. 159 



Engine No. 40 is a vertical single-acting engine with unjack- 

 eted cylinders and a single piston valve fitted with ring pack- 

 ing, one valve serving for both cylinders. The condensing 

 apparatus is a surface condenser with air-pump operated by 

 steam. During the test the exhaust from the air-pump escaped 

 to the atmosphere. This pump was of insufficient size to give 

 a proper vacuum. Steam is furnished by horizontal return 

 tubular boilers. It was found by calorimeter test that at a 

 point near the engine it contained one-half of 1% of moisture. 

 The pistons and the valve were practically tight, although in 

 this class of engines there is always some escape of water by 

 the piston rings into the crank case. The load consisted of a 

 centrifugal pump. 



The feed- water was measured by collecting the water dis- 

 charged from the surface condenser. The quantity thus deter- 

 mined does not include that referred to above, which leaked 

 from the steam cylinders into the crank case, and which there is 

 no ready means of determining. 



The consumption of feed-water here given was less than the 

 actual amount of steam which passed through the engine, 

 owing to the fact above noted that some of the steam which 

 was condensed in the cylinders passed into the crank case and 

 failed to be measured. This accounts for the large proportions 

 which the steam accounted for at cut-off and release bears to 

 the feed-water consumption. In view of the late cut-off, the 

 high back pressure in the small cylinder, the excellent quality 

 of the steam furnished to the engine, and the tightness of the 

 valve, all of which tend to reduce the losses shown by an 

 analysis of the diagram, these proportions must necessarily be 

 large. The leakage referred to could hardly be expected to 

 exceed 5%. Assuming it to be 5%, the feed- water consump- 

 tion would stand 19.1 Ibs., and the proportions of steam ac- 

 counted for at cut-off in the two cylinders .87 and .92 respect- 

 ively. 



