EEVIEW OF FEED-WATER TESTS. 265 



per I. H. P. per hour ; and a similar engine running condensing, 

 with the usual proportions of cylinders, would use not over 

 14 Ibs. The difference between the two is 7.5 Ibs., or about 

 35% in favor of the condensing engine. Allowing, say, 2% 

 for power used by a direct-connected air-pump, and making 

 further allowance, as in the case of the simple engines men- 

 tioned, for the effect of a feed-water heater, the net saving of 

 fuel in favor of the condensing engine is about 25%. 



The effect on a pair of condensing engines produced by run- 

 ning one end of one cylinder non-condensing is shown in two 

 cases. In Engine No. 3 the effect was to increase the consump- 

 tion of feed-water from 21.11 Ibs. to 22.68 Ibs., or about 7%. 

 In Engine Xo. 9 the increased consumption amounted to 

 about 12%. The object of running an engine in this man- 

 ner is to utilize a portion of the steam for heating the feed- 

 water, or for other uses to which exhaust steam can be adapted. 

 If its use is confined to heating feed-water, and the amount is 

 110, or that corresponding to the instances heretofore noted, 

 an advantage would be produced, provided the increased con- 

 sumption did not exceed 11%. If in these two engines the 

 exhaust steam from the single end were used for that pur- 

 pose, there would be a net gain corresponding to about 7% 

 in Engine Xo. 3, and a net loss corresponding to 1% in 

 Engine No. 9. 



V. EFFECT OF SUPERHEATING. 



The effect which superheating has upon the economy of an 

 engine is clearly shown in the case of Engine Xo. 1, where test 

 No. 1 C was made with the steam superheated 82, and test 

 No. 1 B under practically the same conditions, except that the 

 steam was practically dry. This was a simple non-condens- 

 ing engine. The economy produced by the superheating was 

 sufficient to reduce the feed-water consumption from 29.34 

 IbB., }>er I. II. P. per hour, to 26.83 Ibs., or 8.6% or about 

 1% for each 10 of superheating. This may be examined fur- 

 ther by comparing this and other simple engines which use 

 superheated steam with those using ordinary steam. The effect 



