96 ENGINEERING PROGRESS IN THE U. S. NAVY. 



Captain Dyson (Communicated): — Referring to the remarks of Mr. Curtis, 

 while I would be very proud to be alale to assume the responsibility for the design 

 of reciprocating engines used in our modern battleships, I cannot do so without 

 injustice to my predecessors who have been in charge of the Design Division of the 

 Bureau of Steam Engineering, every one of whom has had his share in the develop- 

 ment of this engine. I therefore can deny bias in favor of the reciprocating engine, 

 and shall point out that, on the strength of the presentation of claims made in favor 

 of the proposed installation of turbine machinery on the Nevada by the Fore River 

 Company, I did not hesitate to express myself as being in favor of trying out the 

 turbine machinery proposed for that vessel. 



As to the comparison between the non-existent new North Dakota, and the 

 Delaware, it appears to me that Mr. Curtis is indulging in prophecy based on paper 

 work only. 



Referring to Mr. Anderson's discussion, I shall first reassert my statement that 

 the reduction gear on the Neptune has been perfectly satisfactory in operation. 

 The propulsive coefficient obtained for this vessel basing it on shaft horse-power and 

 effective horse-power, the shaft horse-power being measured forward of the thrust 

 bearing instead of aft as is usually the case, was 62 per cent. If this measurement 

 of power had been taken abaft the thrust bearing, the propulsive coefficient obtained 

 would have been more nearly 65 per cent. The turbines fitted to drive the reduc- 

 tion gear were not entirely satisfactory and new turbines are to be fitted. 



Mr. Anderson denies that the difference in horse-power between the Florida 

 and Utah on preliminary acceptance trial was due to adverse condition of weather 

 during the Florida's trial, and ascribes the difference to difference in propellers and to 

 difference in torsion meters. In answer to this I would state that the Florida's 

 propellers were built from the same plans as those of the Utah, practically the only 

 difference being in the material used, the Florida's screws being of monel metal 

 while those of the Utah were of manganese bronze. If an error is in the torsion 

 meters and the Florida's shaft horse-power curve should be discarded and replaced 

 by that of the Utah, the water consumption, based on shaft horse-power, of the 

 Florida's turbines becomes at once excessive. He further denies the statement 

 that excessive falling off in efficiency of propulsion, due to adverse conditions of 

 wind and sea, the fouHng of bottoms, and to increase of draught, is an inherent defect 

 of turbine ships. In reply to this I would state that both the North Dakota and 

 the Delaware have been standardized when drawing about one foot more than on 

 their preliminary acceptance trials, and when out of dock, in the case of the Dela- 

 ware fifty days, and in the case of the North Dakota seventy days, the two vessels 

 having been together almost continuously during this period. The increase in 

 power required for the Delaware, at 2 1 knots, due to fouling of bottom and this 

 increased draught, amounted to 3 per cent, while for the North Dakota it amounted 

 to 9 per cent; at 19 knots, for the Delaware 6 per cent, for the North Dakota 21 

 per cent; at 15 knots, for the Delaware 2 per cent, for the North Dakota 24 per cent. 



Mr. Anderson makes the statement that a more accurate method of compari- 



