1 88 COMPARATIVE RESUI.TS IN STEAM AND COAL CONSUMPTION. 



Curves 2 and 3. — Speed and revolutions of combination installation, under 

 regular steaming conditions. Curve No. 2 for reciprocating engine; Curve No. 3 

 for low pressure turbines. 



Curve No. 4. — Speed and revolutions for the three-shaft arrangement of tur- 

 bines, as originally installed in yacht. 



Now maximum speed, obtained under conditions shown with Curve i, is 13 

 knots, with Curves 2 and 3 it is 13.70, whereas Curve 4 is carried out to about 16.25 

 knots. 



Colonel E. A. Stevens, Vice-President: — May I ask, Mr. Chairman, in view 

 of Mr. Crane's reflection on our old friend The Indicator, how his curves of indicated 

 horse-power were derived? Were the spots obtained by figuring the indicated 

 horse-power from each set of cards or were curves of mean engine power upon 

 revolutions plotted? I have found in running trials that very small differences 

 of wind would make a decided difference in the mean engine power for given revo- 

 lutions. The same is true of the effect of the rudder if used during run. Plotting 

 separate mean engine power curves for runs with and for runs against the wind, 

 will, I have found, often explain some very puzzling indicator data. 



The Chairman: — Does any other gentleman desire to add to this discussion? 



Admiral H. I. Cone, Member: — May I ask a question, that is, will Mr. Crane 

 throw a little more light on the subject as to whether the ship in these tests was run 

 in combination, at a greatly reduced power; this with a view to get the effect of the 

 exhaust reciprocating engine on the turbine at one-tenth of the power? 



Mr. Crane : — We never ran at less than ten knots. 



Admiral Cone: — I ask this question because these are problems we are 

 attempting to solve — I mean as to the effect when you reduce the power greatly, 

 as we have to do imder naval service conditions — in other words, what effect the 

 introduction of a small amount of steam into a reciprocating engine would have on 

 the turbine when it got to the turbine. 



Mr. Crane : — I think I can answer that when I come to the general answer. 



The Chairman: — Does any other gentleman wish to add to the discussion? 



Mr. George H. Bates, Member: — As a matter of record, I would like to call 

 Mr. Crane's attention to the air pump on the high-pressure engine, one air pump 

 in operation at a time. I thought it might be well to mention that. 



Mr. Crane : — I will answer this discussion, Mr. Chairman. I had hoped that 

 some of the gentlemen who were present at these tests would express some opinion 



