i6o COMPARATIVE RESULTS IN STEAM AND COAL CONSUMPTION. 



In these latter two tests the water was measured in large sized measur- 

 ing tanks in the engine-room, horse-power readings were taken, and the 

 horse-power curves are shown in the appendix. I also show the speed 

 revolution curves in the various conditions, and the slip curves of the three 

 propellers. 



There Vi^ere present at these tests, in addition to the writer and members 

 of his staff, Mr. George Cormack, Secretary, New York Yacht Club, and 

 Mr. Ralph B. Strassburger to whom the writer is indebted for bridge obser- 

 vations, also Mr. George H. Bates and staff from the Staten Island Ship- 

 building Company to whom he is indebted for assistance in the engine-room. 



I wish to call attention to one matter of interest in these slip curves, 

 that even at a considerable negative slip the wing propellers are still devel- 

 oping some thrust, as shown by the fact that the vessel is obtaining more 

 speed per revolution with the turbine propellers working than without them. 



I should also like to call attention to the indicator cards taken with 

 the engine exhausting into the turbines and when exhausting into the 

 condenser, and particularly wish to direct attention to the compression line of 

 the low-pressure cylinder when exhausting into the turbines. 



The summary of the coal and water consumption results of the three 

 types of machinery is appended below. In measuring the water the steer- 

 ing engine steam is included, as it was always exhausting into the condenser. 

 In estimating the amount of water used by the auxiliaries I have used a 

 series of tests made at anchor of these auxiliaries. Apparently in the 13- 

 knot condition with the combination, the propelling machinery is using 

 about 14I pounds per indicated horse-power, with the reciprocating engine 

 alone about 17 pounds, and with the turbines about 20^ pounds. I say 

 "about" because the indicators do not strike me as giving an absolutely 

 truthful account of the amount of power — notice the irregularity in the 

 way the spots run on tlie indicated horse-power revolution curve. 



MACHINERY. 



Boilers:— Two, single-ended Scotch, 16' o" diameter, ii'g" long. Four 



furnaces, 42" diameter, each boiler 81 square feet grate. 



Heating surface, 2,761 square feet each boiler. 

 Engines (Trials of October 5 and 6, 1908, to October, 1909) :— Triple 



screw turbines. High-pressure turbine on center shaft and one 



low-pressure turbine on each side shaft. 



Trials from January, 1910, on: One triple expansion reciprocating 



engine, on center shaft-cylinders, i8|"X29"X45", stroke 26", and 



one low-pressure turbine on each side shaft. 



