196 SUPERHEATED STEAM IN MARINE PRACTICE. 



had shown an economy of nearly 25 per cent, but the earlier economies with the compound 

 engine were fully as much as this, if not more. 



As soon as the compound engine had shown its superiority with steam of moderate 

 pressures (say, 60 to 70 pounds), pressures were gradually increased until compound engines 

 were working with pressures as high as 120 pounds. Then came the triple expansion engine, 

 with a further decided gain in economy, and with gradually increasing pressure. When 

 steam pressures had risen to about the limit for cylindrical boilers, it was natural that 

 designing engineers who sought for greater economy should remember superheat, and begin 

 to experiment with it again. 



I am sure that we all feel indebted to Mr. Oatley for the practical discussion of the 

 question which he has given, and we must remember that he distinctly disavows at the 

 beginning of his paper any intention of discussing superheat itself, but is rather concerned 

 with its practical application. 



Mr. Luther D. Lovekin, Member: — Mr. President and members of the Society of 

 Naval Architects and Marine Engineers, I have read the paper presented by Mr. Henry D. 

 Oatley, entitled "Superheated Steam in Marine Practice," and congratulate Mr. Oatley on 

 his timely, important and interesting paper on this subject. 



It was quite a surprise to me to learn that from twelve hundred to fifteen hundred 

 ships have been equipped with superheaters. I was fully cognizant of the great work done 

 in this country with the Schmidt superheater on locomotives. In fact, I had the pleasure of 

 discussing this subject with Mr. J. T. Wallis, General Superintendent of Motor Power of 

 the Pennsylvania Railroad, at Altoona, Pennsylvania, a short time ago, and Mr. Wallis 

 showed me at that time the daily records of locomotives equipped with and without super- 

 heaters on regular runs between New York and Philadelphia. The actual savings in coal 

 averaged more than 30 per cent. 



Mr. C. D. Young, Test Engineer of the Pennsylvania Railroad, delivered a most inter- 

 esting lecture on the subject of superheating before the Franklin Institute recently, in which 

 he gave the actual results of probably the most exhaustive tests ever conducted on the 

 Schmidt superheater, and to anyone who may be at all interested in the subject of super- 

 heating a reference to this work would be invaluable. I personally know that as a result of 

 these tests a piston valve which was formerly 15 inches in diameter, "before superheaters 

 were being used," has since been cut to 12 inches in diameter for the same amount of work. 

 The reduction in the piston valve enabled the valve gear to be reduced in weight, and con- 

 sequently the inertia forces have been greatly reduced, which is also an item of great impor- 

 tance in locomotive work. 



I notice the author questions the railroad men talking eloquently and continually of fuel 

 economies of 25 to 35 per cent, but when we consider the great value that the Schmidt super- 

 heater has shown for locomotives in actual service, and know from actual experience that 

 results of 30 per cent, and more, have actually been obtained, we can readily understand 

 why the railroad men are so enthusiastic. As Mr. Oatley justly remarks, to expect this in 

 marine practice is, of course, out of the question. Personally I am inclined to believe that 

 we have as yet a great deal to learn as to just what the real difference in economy is between 

 marine engines fitted with superheaters and without superheaters, for the reason that very 

 few tests have been made on a vessel having the same machinery with and without super- 

 heaters. 



