ELECTRIC PROPULSION OF SHIPS. 137 



the question obtain the August, 1920, issue of that journal and see the other view, in the article 

 "U. S. Battleships of the Year 1914 and Later Classes." 



I was much interested in listening to Captain Newman's remarks regarding the per- 

 formance of the new coast guard cutters, but unfortunately very little was said regarding 

 the actual fuel performance of the electric geared machinery. 



The Army and Navy Register, in its issue of September 10, gave particulars of the 

 trials of the U. S. S. Tampa. It was a short article and one paragraph read as follows : 



"The total fuel consumed on the four-hour run was 2,008 gallons. The consumption 

 was high on account of unsatisfactory pump operation." That is all. As Captain Newman 

 stated, the contract conditions of the vessel were as follows: Knots, 16.00; S. H. P., 2,600; 

 revolutions, 130. There are superheaters also installed on these vessels, and if you use the 

 design figures as a basis, you will find that the fuel consumption averages about 1.35 pounds 

 of oil per S. H. P. per hour for all purposes. 



President Capps in the chair. 



Mr. Elmer A. Sperry^ Member: — The Society is certainly to be congratulated upon 

 the paper by Mr. Thau as making a substantial contribution to our Transactions. 



The paper devotes considerable space to Diesel-electric transmission. We all appreciate 

 the suitability of the turbo-electric drive, where the turbine needs assistance in the fact that 

 it will only run one way and is almost impossible when asked to go through severe maneu- 

 vers. But with the Diesel or oil engine the matter is entirely dififerent. Here we have an 

 arrangement which will nm one way as well as the other, and in quick reversing may be 

 made about the equal of the reciprocating steam engine. 



In the case of the oil engine the greatest problem is simplified over the turbine in two 

 ways. The speed is lower, and the other important difference is that the oil engine gives 

 full and quick reversing, so we do not need the electric plant for the purpose of reversing, 

 as we do with the turbine. 



We should look at this matter squarely. The electric propulsion of ships is good and 

 should be used if we do not know any better way. However I, for one, believe that there is 

 a better way in the heavy duty air-gap drive that has now been under test for upwards of two 

 years, and I give fair warning that this may be found to entirely supersede the electric pro- 

 pulsion of ships. It makes a number of substantial contributions, not the least of which is 

 the opening up of new fields of usefulness for reciprocating oil engines by permitting gear- 

 ing, and comparatively inexpensive gearing, to be directly driven therefrom under conditions 

 of practically no wear and with entire success. 



Many attempts have been made to drive gears with reciprocating engines, but the 

 crank-whip and general thrash due to the irregularities in the crank effort have inter- 



