86 ENGINEERING PROGRESS IN THE U. S. NAVY. 



as ratios of expansion have increased, but to proceed further in this direction 

 in marine practice, steam pressures must be increased, as the point of cut-off cannot 

 be advanced. 



Quadruple expansion or quintuple expansion engines will be relatively as 

 superior in economy to triple expansion engines as triple expansion engines were 

 found to be in advance of compound engines. Quadruple expansion engines of 

 proper design have already demonstrated their great superiority in the matter of 

 economy to triple expansion engines, as is well known. Knowledge in the art of 

 manufacturing high grade materials has advanced steadily, and it has now reached 

 a point where very much higher steam pressures may be carried with safety. There 

 is absolutely no doubt that engines and boilers can be built to withstand any pres- 

 sure desired up to 500 pounds absolute. This pressure when compared with Diesel 

 engine practice is low, and Diesel engines undoubtedly are being operated success- 

 fully now, in so far as strains on parts are concerned. 



Engines and boilers must be entirely redesigned to conform to such pressures, 

 and in doing so it will incidentally be found that some of the forms already adopted 

 in boilers have been very far from perfection. With a pressure of 465 pounds 

 absolute at the engine, a superheat of 40 degrees might be carried on the seven 

 vessels of the Navy fitted for 85 degrees superheat referred to. 



I claim for relatively higher steam pressures these benefits: — 



1. Greater economy in steam and therefore in fuel consumption per horse- 

 power. With 465 pounds steam at the engine close to 15 per cent in steam con- 

 sumption would be realized over present practice. 



2. Decreased size of steam cylinders, steam pipes, feed pipes and boiler plant. 



3. Reduction of weights in engine and boiler rooms. 



4. Decrease in space required for machinery and fuel. 



5. Decrease in fuel required for a given radius of action. As the total heat 

 units required to be absorbed by the boilers are less for quadruple or quintuple 

 expansion engines than for triple expansion engines, the machinery spaces and 

 weights could be reduced accordingly. 



Mr. Walter M. McFarland, Vice-President: — I have only a word to say, but 

 not in the general discussion of the paper. I called the attention of one of the 

 speakers to the fact that he has made a broad general assertion which flatly con- 

 tradicted a statement in the paper, and I thereby gave him an opportunity to 

 correct what I thought was an obvious slip on his part. He did not make that 

 correction, so I must state the facts myself. The paper by Captain Dyson states 

 distinctly that the gearing on the Neptune has been a decided success. In the pro- 

 ceedings of another society there was a paper by the chief engineer. Lieutenant 

 Smith, descriptive of the whole ship, which went into great detailabout the gearing. 

 Lieutenant Smith said the same thing— that the gearing has been a decided suc- 

 cess. I do not want to detract at all from the credit which is due to Sir Charles 

 Parsons for what he has done. I know the Vespasian was actually operating at 



