200 ENGINE TESTS. 



Engine No. 50 is a cross compound engine with horizontal 

 steam jacketed cylinders and a jet condenser operated by a 

 direct connected air-pump. The jacket of the L. P. cylinder 

 forms a thoroughfare through which the steam is supplied to 

 the steam chest, the steam being admitted through the bottom. 

 The jacket of the H. P. cylinder drains into the receiver. The 

 drip of the receiver and of the low-pressure jacket passes to a 

 pump operated by the engine, and thence to flue heaters, or 

 " regenerators " as they are called, which are located in the flue 

 of the boilers. The steam generated in these heaters returns 

 to the receiver. By this means the low-pressure cylinder 

 receives benefit from some of the heat which would otherwise 

 escape from the boilers to the chimney. Steam is supplied 

 from vertical boilers, which superheat. The exact amount of 

 superheating was not determined ; but from the operation of 

 boilers of similar type, the temperature was probably 30 above 

 the normal. The piston of the high-pressure cylinder leaked 

 considerable, but the piston of the low-pressure cylinder and 

 the valves of both were in good condition. The load was that 

 of a cotton mill. 



The results of this test are interesting on account of the 

 means provided for reheating the steam and re-evaporating the 

 jacket water for the use of the low-pressure cylinder, employ- 

 ing for this purpose the heat of the waste gases of the boilers. 

 Comparing this test with that made on Engine No. 49, where 

 no such provision was made, the difference is quite marked, 

 being .9 of a pound per I. H. P. per hour, or nearly 7%. It is 

 difficult to determine by this comparison how much, if any, 

 effect was produced by the reheating process, because of the 

 difference in the condition of the steam ; and, furthermore, 

 because there was quite a difference in the degree of expansion, 

 the cut-off in the high-pressure cylinder of one engine being 

 .33, and in the other .27. The effect of the reheating is not 

 sufficiently marked to show in the analysis of the diagrams. 

 It appears that there was no more steam accounted for in the 

 low-pressure cylinder in one case than in the other. A greater 

 quantity might be expected if there was a marked effect pro- 

 duced by the reheating. 



