98 ENGINE TESTS. 



by an independent air-pump driven by steam. The engine \A as 

 supplied from horizontal return tubular boilers, and the steam 

 on subsequent occasions was found to contain 1.2 / of moisture. 

 In the matter of leakage, the engine was in fair condition, 

 though every valve, and the pistons as well, showed a small 

 amount of leakage. The load was made up largely of rubber 

 grinding machinery. 



Two tests were made, one with the condenser in operation, 

 and the other with the engine exhausting into the atmosphere, 

 the condenser being stopped. Independent tests were made, 

 showing the quantity of steam used by the air-pump ; and 

 allowance has been made for it. Besides the engine, the boiler 

 supplied the feed-pump and a tank-pump, The steam thus 

 used has not been allowed for. 



The air-pump, which had a single steam cylinder 10" in diam- 

 eter and 24" stroke, when making 56.3 single strokes per 

 minute, was found to use 1682 Ibs. of steam per hour. The 

 power developed amounted to 12.8 H. P. ; consequently the 

 air-pump consumed 131.7 Ibs. of steam per I. H. P. per hour. 

 On the condensing test the air-pump used over 13 per cent of 

 the entire quantity consumed by the engine. 



The quantity of steam used by the engine and air-pump 

 working condensing was about 12 % less than that used when 

 the engine was running non-condensing, and the quantity used 

 by the engine alone about 24 % less. 



In explanation of the comparatively low proportion of feed- 

 water accounted for on the condensing test, it is probable that 

 allowance made for steam used by the condenser was less than 

 the actual quantity, owing to the fact that ordinarily the 

 cylinder drips were kept partially open. On the condenser 

 test, these were closed. Probably the actual consumption of 

 feed-water was somewhat below the 23 Ibs. given in the table, 

 and the actual proportions referred to were somewhat higher. 

 It should also be noted that the portion unaccounted for in- 

 cludes the steam used by the boiler-feed and tank-pump on both 

 tests, probably 2 or 3 % of the whole. 



