ELECTRIC PROPULSION OF A BATTLESHIP. 75 



Charles Parsons." As the author then calls attention to the simplicity of piping, steam and 

 vacuum connections with the electric drive as compared with other methods, and states that 

 the California had two turbines, the Utah ten and the proposed Parsons geared equipment 

 thirty-two, he evidently wishes it to be understood that the basis of comparison proposed is 

 one worthy of our consideration. 



Plate 39, which we are asked to compare with the layout of the California, is taken from 

 a paper entitled "Mechanical Gearing for the Propulsion of Ships," read on March 13, 1913, 

 before the Institution of Naval Architects; the sketch from part of Plate VII accompanying 

 this paper, the title being "Geared Turbine Machinery for Battleships with Separate Cruis- 

 ing Installation." The description in the paper refers to it as "a further design for a 

 battleship of about 60,000 shaft horse-power with geared turbine machinery on four shafts, 

 which also includes an additional set of small turbines and gearing for use when cruising." 



We have this arrangement put before us for comparison with the California, when on 

 Plate VI of the same paper is illustrated the "Typical installation of geared turbine machin- 

 ery for a battleship," which is described as follows: — "Design for a battleship of about 

 40,000 horse-power with four shafts at 200 revolutions per minute." In the arrangement 

 illustrated there are two turbines geared to each shaft, the turbines on the two shafts on 

 either side of the ship being arranged in the well-known four-cylinder triple formation, each 

 group consisting of a high-pressure, intermediate-pressure, and two low-pressure turbines, 

 an arrangement which leads to a high efficiency both at full power and at cruising speed. 

 With this typical arrangement illustrated in the same paper and described in the way that it 

 is, it hardly seems fair to put before us the special arrangement shown by the author in Plate 

 39 of his paper as if this were the regular Parsons geared arrangement for a battleship. 



Mr. John F. Wentworth, Member: — Last year I made some remarks on the pres- 

 ent subject in connection with the paper read by Mr. Robinson. The questions which I 

 asked were not answered to my satisfaction. No doubt a good deal of the fault lies in the 

 fact that I was not favored by being present at some of the early discussions on this subject 

 by Mr. Emmet. Perhaps he can clear this matter up at this time so that I may be able to 

 understand the reason for this type of marine plant. 



My understanding of the proposition is that the advantage lies in its greater efficiency 

 as compared to the reciprocating type of engine. As I und'erstand it, of the power of the 

 turbine about 7 per cent is wasted in producing current in the generator. Then from 5 to 

 7 per cent of the output of the generator is wasted in the motor. This waste comes about 

 because the turbine is not well suited for direct drive of large-sized marine propellers. 



In reply to my questions of last year, when a comparison was made between oil engines 

 and the turbo-generator plant, the oil engine was condemned on account of its present state 

 of development. Apparently the mistake was made in supposing that I was advocating 

 some of the present Diesel engines. There is but one Diesel theory, and all the present engines 

 show signs of the Diesel fallacy which last year I attempted to prove, and which proof can 

 be accepted in view of the lack of any attempts to refute my statements. 



The next point to be taken up in the reply was the record of the sister ships Jupiter 

 and Cyclops. An efficiency curve for the Jupiter was plotted from the two points given in 

 Lieutenant Robinson's paper. This was of course a straight line. The efficiency curve of 

 the Cyclops was drawn in from the comparison of the fuel consumptions at the same speeds 

 with the efficiency of the Jupiter. Where the efficiency of the Jupiter at 10 knots was 



