ENGINEERING PROGRESS IN THE U. S. NAVY. 85 



boilers the Diesel engine may be installed for cruising purposes to use the same grade 

 of fuel as is burned in the boilers. By this method the cruising radius of the battle- 

 ships, cruisers or destroyers can probably be more than doubled. One remarkable 

 advantage that is apparent in the Diesel engines is that the fuel per horse-power is 

 nearly as low at small powers as it is at the higher powers. 



We have not yet made attempts in this country to install Diesel engines for the 

 main propelling machinery in ships of the destroyer type or cruisers or battleships, 

 but such engines are being installed on our submarine boats. It is my opinion 

 that we must soon turn our attention to using the internal-combustion type of 

 engine, probably in conjunction with turbines, for our large-powered naval ships. 



Mr. R. C. MonteaglE, Member: — This paper, though brief, is an admirably 

 clear presentation of engineering progress in the Navy, and in reading it one cannot 

 escape the conclusion arrived at by the Bureau of Steam Engineering, viz., that of 

 placing reciprocating engines in heavy vessels of comparatively moderate speed. 



The supplanting of steam-driven reciprocating engines is not imminent, nor 

 do I beHeve such will be the case until every means has been exhausted to increase 

 the efficiency of reciprocating engines, reduce their weight, and the space which 

 they occupy. The various means of increasing such efficiency have not been 

 exhausted, and the direction which I believe to be the most important, in which 

 improvements to reciprocating engines is to be found, has been neglected. I refer 

 to the increase of steam pressures. By increasing steam pressm-e, we at once have 

 (with correct engine and boiler design) increased economy, reduction of weight, 

 and reduction of space occupied by machinery and fuel. The pressure mentioned, 

 viz., 265 pounds gauge pressure, is much too low to effect the economies attainable. 



Steam presstures have not kept step with progress in other directions. If they 

 had, they would now be approaching 500 pounds absolute instead of 280 pounds 

 absolute. 



In 1899 six cruisers were built for the U. S. Navy. These were fitted with 

 Babcock & Wilcox boilers whose pressures were 290 pounds absolute. That is 

 now thirteen years ago.. Why has a halt been called on increased pressures? 

 Is it because of difficulty in getting suitable piston packing or suitable metallic 

 packing for the rods? Or is it because boilers in their present form cannot with- 

 stand these higher pressures? If so, these objections are trivial, for they can be 

 obviated. Rise in temperature has been regarded by many as an argument against 

 higher steam pressures. But when it is reahzed that there is only a difference of 

 56 degrees in temperatture between 280 pounds and 500 pounds absolute, this 

 objection is seen to be invalid. 



Large compound reciprocating engines of the horizontal type, in stationary 

 plants, are using 150 pounds pressure and 150 degrees superheat with perfect 

 success, equal to a temperature of 51 1 degrees. The horizontal type of engine, it is 

 needless to say, operates under more severe conditions than any possible design of 

 vertical engine, marine or otherwise. A distinct gain in economy has been made 



