BATTLESHIPS. EXPERIENCE GAINED ON THE JUPITER. 203 



than 1 pound of oil per horse-power for all purposes. This does not constitute the main 

 unit alone, but all units, auxiliaries included. Our figures have proven this beyond all doubt. 



Another advantage with the electric drive is the fact that you can make a really elec- 

 trical battleship, using your power at the very conservative rate of, say, 1 pound of oil per 

 horse-power, and using very efficient turbines for generating the current for driving the 

 auxiliary machinery, instead of using from 100 to 200 pounds of steam per horse-power, as 

 we are doing to-day in lots of our auxiliaries on battleships. 



I feel it my duty to move that this Society offer its congratulations to Mr. Emmet for 

 his painstaking work in bringing about a new means of propelling vessels, and particularly 

 battleships, which marks a new epoch in marine engineering and goes far into that most im- 

 portant question of the day, viz., the conservation of our natural resources. 



I think Mr. Emmet has done more than any one else to bring about that result. 



Mr. E. a. Stevens, Jr., Member: — I do not agree with Mr. Emmet in what he said 

 about the reciprocating engine no longer having a place on board ships. There are places 

 where, I think, the use of this type of engine will never be abandoned, especially in slow-speed 

 work, and on vessels handled by crews that are paid small wages, such as tugs, small tramp 

 steamers, etc. It is true you can get better economy with a geared turbine or with Mr. 

 Emmet's electric propulsion system, but I do consider that a high-speed machine, such as 

 this turbine, relying on force lubrication and close attention for its satisfactory operation, 

 should never be put into such hands. Therefore I think what Mr. Emmet has said about the 

 reciprocating engine is a little far-fetched. 



In regard to the economy of the Jupiter, I would like to call your attention to page 190 

 of this paper where Lieutenant Robinson states that the propellers were designed by Captain 

 Dyson, and showed a high efficiency of propulsion, from 300 to 800 horse-power less than 

 her sister ship. I take this to mean that at the lower speed she drove with 300 horse-power 

 less, and at the higher speed 800 horse-power less. Looking at the result of the trial, we find 

 the Jupiter took a little over 7,000 horse-power (on the propeller). The saving in power 

 alone due to the propellers is over 10 per cent, leaving less than 15 per cent saving (of fuel) 

 due to the type of machinery. 



What Lieutenant Robinson has said about the economy of the Jupiter would equally 

 apply to geared turbines, especially at the higher speeds. I do not think, however, that there 

 would be much difference in favor of the electric propulsion, at the lower speeds, as the effi- 

 ciency of the electric machinery would not be as great as at the higher powers, while the 

 losses in the gears would not vary much. I do not believe that any reduction can be made in 

 the crew, for whatever is saved in the number of machinists carried, if any, will have to be 

 supplanted with electricians. In the case of any electrical trouble the help that would be ren- 

 dered by most marine engineers would be of little assistance, as I am quite sure that most of 

 them know very little about electricity. What they do know they have learned in connection 

 with small plants, electric lighting, air compressors, winches, etc., such as are used on vessels. 

 They would, however, know very little about an electric power plant generating and using 

 several thousand horse-power, with its complicated accessories. Some people contend, if 

 more were known about electricity by marine engineers, that this system of propulsion would 

 be more popular. Be that as it may, I fully believe that if they did know more about elec- 

 tricity, they would be less likely to want it as a means of propulsion. 



