FIREPROOF PASSENGER STEAMER. 175 



with the exhaust steam from the auxiUaries. The turbine-driven auxiliaries 

 have been proportioned to furnish about 90 per cent of the steam required 

 to heat the feed water to 208° F. and a hve steam connection will be 

 provided for the additional heat should its use be desirable. Suitable 

 atmospheric exhaust connections and valves are provided, and the auxiliary 

 exhaust has an oil separator in front of each heater, although but little oily 

 steam will be present as most of the auxiliaries are turbine driven. All of 

 the small turbine bearings are ring-oiled and will require very little attention. 



Immediately astern of the condensers and auxiliaries are the three 

 1,000 horse-power induction motors and the thrust bearings. These motors 

 are very generously proportioned. They have 24 poles and a normal speed 

 of 300 revolutions per minute. They are provided with collector rings and 

 are controlled by means of varying the external resistance. The motors 

 and generators are so designed that the current under a dead short circuit 

 does not exceed two and one-half times full load current. 



The controllers for the three motors are in the pilot-house and are 

 fitted with interlocking devices as well as an automatic timing device. All 

 the motors may be started, brought to any speed up to full speed, reversed 

 or stopped by the manipulation of the three controller handles, one for each 

 motor. In addition, signalling devices are installed in both engine-room 

 and boiler-room as well as the usual bell and speaking tubes. 



The fire-rooms, two in number, each containing four water-tube boilers 

 in two batteries, are located forward of the machinery space. The coal 

 bunkers are in the wings on either side of the batteries. Each boiler has 

 1,635 square feet of heating surface and 44 square feet of grate surface. 

 The steam pressure will be 250 pounds gauge and the steam will be moder- 

 ately superheated. The steam main is in duplicate with cross connections, 

 as is the feed-water main, and both are of the highest grade. The steam 

 piping is of steel pipe with Van Stone joints, steel flanges, fittings and valves. 

 The feed piping is brass with brass valves and fittings. All boiler connec- 

 tions have two valves between the boiler and the pressure main, and the 

 automatic stop-check valves usual in the best power-house practice will be 

 installed. Each boiler is provided with steel, extra heavy safety valves 

 of navy pattern. 



The boilers are served by three stacks, one for the forward pair, a 

 large one for the middle four boilers, and one for the after pair. These 

 stacks are 6 feet 6 inches and 8 feet in diameter and 72 feet above the 

 grates. Forced draft has been provided for, but the machinery will not be 

 installed. 



