198 SUPERHEATED STEAM IN MARINE PRACTICE. 



has influenced marine engineers with regard to the adoption of superheat. If you use super- 

 heated steam with high-pressure turbines, the part of casing which is subjected to the high 

 temperature steam requires to be made of cast steel, and it has been very difficult to obtain 

 sound castings from the foundries. I must say, however, that they are now turning out very 

 much better work in this respect. The blading, too, has to be of special material, and by 

 making this of copper, superheat can be used with complete success in marine work as it 

 has in the past with land installations. As the author says, I think superheated steam is 

 going to be used in marine turbines very largely in the future. 



Mr. E. H. Peabody, Member: — I would like to say a few words in this discussion on 

 my own behalf. I think that this Society is greatly indebted to Mr. Oatley for again bring- 

 ing before it the importance of, and particularly the great increase in the use of, superheated 

 steam. There has been too much of a tendency, I think, in this country, to attribute troubles 

 to the superheaters which really should never have been attributed to them, and not enough 

 effort has been made to overcome some slight troubles which were due to superheaters. 



I remember that the first superheater I had any experience with was in connection with 

 a stationary plant and Corliss engine, and after some weeks of experimentation the super- 

 heater was thrown out, because the engine would not take care of the superheat. In that 

 case, doubtless, the situation was exaggerated, and the superheater was much less expen- 

 sive than the engine. I only mention the incidi.nt as showing the tendency which we have 

 sometimes had in regard to superheaters. We do not work sufficiently hard to obtain the 

 undoubted advantages of superheat, although, as Mr. Oatley says so well, the use of the 

 superheater is increasing and is bound to increase. Probably no element in a steam plant 

 to-day pays so high a return on the investment as the superheater. 



The President: — Is there any further discussion on this interesting question? If not, 

 we would like to hear from Mr. Oatley in closing. 



Mr. Oatley : — I am pleased to have Mr. Lovekin submit the plate which he men- 

 tions, and which illustrates a modified arrangement of his superheater boiler. This will be 

 substituted for the one shown in the paper. That which I used was the only one available 

 at the time the paper was printed for distribution. 



Mr. McFarland has expressed my sentiments very fully in his tribute to Mr. Isherwood. 

 I fully appreciate the grand work which he has done in various lines, and especially with 

 regard to his most carefully conducted and valuable experimental work along the lines of 

 efficient use of steam. In the list given in my paper there was no thought of omitting any 

 credit which we all know is due to Isherwood, but the names given in the paragraph referred 

 to by Mr. McFarland and also in paragraph 27 were those of men who had designed and 

 built superheaters, while Isherwood's connection with superheated steam was more that of 

 an investigator and user of superheating apparatus. 



Mr. McFarland's reference as to reasons why superheating remained quiescent for so 

 many years are undoubtedly big factors, though I cannot help but feel that they were secon- 

 dary rather than primary causes. I feel very sure that had some of the present designs 

 of superheaters been available and had good steel castings and high grade steel in its various 

 forms been at hand, the development and ase of the superheater would have progressed 

 rather than been crowded aside entirely by the introduction of the compound and later by 



