ENGINEERING PROGRESS IN THE U. S. NAVY. 71 



ment with remarkable results by Captain Dyson himself, the latter representing a 

 type of turbine which was new, and which had undergone practically no develop- 

 ment at that time. When the North Dakota's turbines were designed — about six 

 years ago — but little importance was attached to economy at low speeds. The 

 builders were not asked to make any effort in this direction, and the turbines were 

 designed simply to meet the actual guarantees called for by the Department. 

 These and the results obtained on trial were as follows : — 



WATER PER HORSE-POWER (lNCI,UDING SHAFT HORSE-POWER OP MAIN TURBINES 

 AND INDICATED HORSE-POWER OF ENGINE-ROOM AUXILIARIES). 



Guarantees. Actual trial results. 



At full power 15 . i lbs. 13-48 lbs. 



At 19 knots 16. 1 lbs. 15.37 lbs. 



At 12 knots 23.2 lbs. 22.88 lbs. 



The turbines thus met the guarantees in all respects, and were duly accepted. 

 The excellent results at low speed subsequently obtained by the Delaware which 

 were largely due to the improvements introduced by Captain Dyson, were not then 

 anticipated, at least so far as we knew. 



I have no doubt that Captain Dyson used the North Dakota's results for 

 comparison with the Delaware, because there is no other battleship equipped with 

 this type of turbine in this country, and I have such faith in Captain Dyson's 

 fairness that I feel sure he had no intention of making an unfair comparison. Never- 

 theless the comparison is, in my judgment, quite unfair, and should not be con- 

 sidered except in conjunction with the improvements that have been made since 

 that time. 



Last winter a battleship was awarded to the Fore River Company which will 

 be equipped with a more highly developed form of Curtis turbine, designed to give 

 much higher economy under all conditions, particularly at low speeds. I believe, 

 therefore, it will be illuminating to analyze the probable performance of this new 

 ship, called the Nevada. Instead, however, of comparing one ship directly with 

 another, which is always unsatisfactory where the models and the speeds are dif- 

 ferent, I will make the comparison between the old North Dakota and an assumed 

 or new North Dakota, exactly like the old ship except that it is to be equipped with 

 turbines and screws like those which are going into the Nevada. Such an improved 

 North Dakota will be better than the old ship; first, because the turbines will be 

 more efficient, that is, they will require less steam to develop the necessary shaft 

 horse-power; second, because the screws will be more efficient for the reason that 

 they are larger and slower turning, that is, they will require less shaft horse-power 

 to develop a given speed of ship. 



Plate 42 shows the actual water-rate curve of the main turbines of the North 

 Dakota at different speeds of ship obtained on the official trials (no auxiUaries 

 being included). It also shows the expected water-rate curve of the improved 



