ENGINEERING PROGRESS IN THE U. S. NAVY. 57 



In the cases of the main engines of the three scouts, Birmingham, Salem, 

 and Chester, the Birmingham, with reciprocating engines, has always been 

 ready for service, while her two sisters have been repeatedly laid up at the 

 yards for overhaul of the main turbines. 



Evidence of experience leads to the conclusion that a battleship fitted 

 with reciprocating engines for propelling purposes is much less apt to be 

 forced off her station by necessary repairs to her engines than is one fitted 

 with turbine engines. 



Condition (e) — Reliability of Machinery when Driven at High Powers. — 

 From the natures of the two machines, it would appear to be safe to decide 

 this condition as being distinctly in favor of the turbines, as this type of 

 engine is completely free from all reciprocating parts held together by bolts 

 and nuts. 



Experience with the Delaware's engines, however, leads to the conclusion 

 that where proper care is taken to lock all nuts securely, and to effectively 

 protect the engines against the shocks of reversal of direction of motion, the 

 reciprocating engine can, even here, be regarded as nearly on a par with the 

 turbine in reliability. 



The full-power twenty-four hour run of the Delaware, made without 

 preparation immediately after her arrival home from Chili, demonstrates 

 this reliability of the present type of battleship engines very thoroughly. As 

 stated, without any preliminary preparation of engines or machinery, the 

 vessel put to sea, and upon getting well clear of the land a full-power run of 

 four hours was started, during which time the vessel averaged 21.86 knots 

 per hour. Without intermission the vessel continued on for twenty hours 

 longer, averaging for the full twenty-four hours a speed of 21.3 knots, the 

 ship automatically slowing down as the fires became dirty and the personnel 

 fatigued. 



Upon the completion of the trial a radiogram was received from the 

 commanding officer of the vessel reporting that not the slightest disarrange- 

 ment had occurred to either the main engines or the auxiliary machinery, 

 and that she was ready for immediate service. 



Condition for Minimum Weight and Space Required for the Propelling 

 Machinery. — As already shown, the total heat units required to be absorbed 

 by the boilers, both for Parsons turbines and for reciprocating engines, with 

 battleships of the speed and power that now exist, is practically the same in 

 both cases at full power. This indicates that, for existing conditions, noth- 

 ing can be saved in the boiler-room weights or space by adopting turbines, as 

 the same boiler power is required in the two cases. 



In the engine-rooms, for these powers, however, the reciprocating engine 

 has a decided advantage in both weight and space required. 



