ENGINE No. 52. 207 



Engine No. 52 is a pair of horizontal tandem compounds, 

 having jacketed cylinders and reheating receivers, the con- 

 densers being of the siphon type, to which water is supplied 

 by gravity. The H. P. cylinders are jacketed all over, but the 

 L. P. cylinders have only the barrels jacketed. As in the case 

 of Engine No. 51, the reheaters are provided with sufficient 

 surface to superheat the steam passing to the low-pressure 

 cylinders, the water which remains being trapped. The valves 

 are all of the gridiron type. Steam is supplied by horizontal 

 return tubular boilers, and at the throttle valves it contained 

 .1 of 1 % of moisture. The H. P. pistons leaked to some ex- 

 tent, and the head-end exhaust valve of the left-hand low- 

 pressure cylinder leaked a considerable amount. The pistons 

 of the H. P. cylinder and the remaining valves were fairly 

 tight. The load was cotton machinery. 



Three trials were made with three different receiver pres- 

 sures, and a fourth trial with steam shut off from the jackets 

 and the reheating tubes. 



Comparing the results of these tests with those made on 

 Engine No. 51, which is of the same general type and of 

 about the same power, but having only half the number of 

 cylinders, there is a striking difference. This engine did not 

 have the benefit of superheated steam as did Engine No. 51, 

 and this difference in the conditions must be taken into account ; 

 but it is hardly possible that the whole of the difference, which 

 is about 9 %, could be produced in this way. There may be 

 some difference, also, in the amount of leakage of the two en- 

 gines. Engine No. 51 had the benefit of the best vacuum. 

 Making all allowances for these differences, it is quite certain 

 that the size of the cylinders had some effect upon the results. 

 The action of the steam in the cylinders is quite different in 

 No. 52 from what it is in No. 51 ; but it will be noticed that 

 steam accounted for in the low-pressure cylinders is greater than 

 that shown in the high pressure cylinders, whereas in Engine 

 No. 51 the contrary is true. 



Comparing Test " C " with jackets on, and Test " D " with 

 jackets off, the difference in the economy shown is only .26 of 



