200 THE APPLICABILITY OF ELECTRICAL PROPULSION TO 



of them will run the ship with only slightly less efficiency. Another point is that an electrical 

 alternator is not exactly a unit, but is an assembling of a great number of magnetic circuits, 

 in separate coils, and is not likely to be injured so it cannot be reconnected in some way so 

 that it will run by a man who understands. I guarantee that I can give a man a little while 

 with a pickaxe on the Jupiter's electrical apparatus, and if I had a few hours at it I would 

 get it running again, because there are ways of doing these things. People who understand 

 that kind of electrical apparatus can do all sorts of things with it which would seem to be 

 most difficult at a glance to the layman. 



The comparison which is now most interesting in this connection is that with the geared 

 turbine, which has become most important as a method of ship propulsion. From the dem- 

 onstrations which have been made with both of these methods, it is obvious that no ship 

 should be run with reciprocating engines or direct turbine drive. The geared turbine is sub- 

 ject to various limitations, as compared with the electric drive method, which have sometimes 

 been overlooked. I had a geared turbine set running in Schenectady driving a 500-kilowatt 

 generator. I decided to determine what the losses in reversing a turbine would be, so I ran 

 the generator as a motor, first in one direction with various pressures, with various degrees 

 of vacuum in the casing, and then in the other direction with the same conditions. We de- 

 livered 10 kilowatts to the motor by running the turbine ahead and delivered over 70 kilo- 

 watts to the motor by running it backward, that is, against the direction of the buckets. It 

 appears, therefore, that turning these buckets in the reverse direction takes some power. The 

 degree of this loss will depend upon circumstances, and in some of the higher speed and 

 best turbines the loss will be very considerable. If, however, we want the best we cannot 

 make concessions in the design of the turbines ; we must go to the limit in speed and in every 

 characteristic, or else we will lose more than the electrical losses. The mechanical losses of 

 the gears amount to something, maybe a per cent or two, and the additional number of bear- 

 ings involved through the necessity of alignment of the gearing and the supporting of weights 

 and thrusts or pressures from the gears involve additional losses. The reversing turbine, as 

 has been stated, involves losses, and if it is to give powerful and effective reversing power, 

 which is important on any ship, its losses will be considerable. The electrical losses in the 

 California design represent less than 8 per cent, and the turbines are of ideal efficiency. 



To give you a conception of how such a turbine compares with the turbines used to pro- 

 pel ships, there is a large turbine which we are operating here in New York, and tested within 

 the last few days, which delivers 30,000 kilowatts. At about 25,000 kilowatts, or possibly 

 27,000 kilowatts, two of these machines would be capable of driving the Lusitania. The effi- 

 ciency of that machine is 75 per cent of the theoretical work in the steam, that is, delivered 

 electrically to the busbars. If we took the electrical losses out of that, which will amount to 

 about 5 per cent, we will raise that to about 77 or 78 per cent. The Lusitania's turbines, 

 which I suppose are the most efficient marine turbines in the world, are about 63 per cent effi- 

 cient, so you have a comparison of two things, for the same purpose, except for the auxil- 

 iary arrangements of the turbine of 78 per cent efficiency, as against the one of 63 per cent 

 efficiency and in such a case the electrical losses could be at least compensated for by using 

 lower speed propellers which would be much more efficient. The Jupiter's turbine is not so 

 good as that, quite, because it is not so large, and it is only in the largest turbines we can get 

 the best results. The California's turbines at the best speeds will be almost as good as this 

 highly efficient machine which I have mentioned. 



In turbine drive of ships you can make practically no concessions as to the speed of the 



