BATTLESHIPS. EXPERIENCE GAINED ON THE JUPITER. 193 



are placed on these gaskets. The top header rests on gaskets on the tops of the small 

 cylinders. The rheostats are supplied by water either from the main circulating 

 pumps or the flushing pump. These rheostats are capable of running under full 

 load for an indefinite length of time. 



The main switchboard is supplied with a voltmeter, ammeter and indicating 

 wattmeter for the main generator, with a voltmeter and ammeter for the field of 

 the generator, with a frequency and speed indicator for main generator, with am- 

 meter and recording wattmeter for the motors, with "ahead" and "astern" oil 

 switches for the motors, with a field switch for the main generator, and with a rhe- 

 ostat and switch for the field of the exciter. The control stand is in front of the 

 center of the switchboard. The "ahead" and "astern" oil switches have mechanical 

 interlocks so that the "ahead" and "astern" switches for a motor cannot both be 

 thrown in at the same time. There is also a mechanical interlock from the short- 

 circuiting levers to the oil switches, which prevents the oil switches from being 

 thrown in when the rheostats on the motors are short-circuited by the levers. 



The operation of the machinery may be divided into three different condi- 

 tions. Starting with all auxiliaries in operation, the turbine running, and an ex- 

 citer cut in on the field of the generator, the operation under different conditions 

 would be as follows: — 



1. Getting under way, coming to anchor, going alongside a ship, or, in gen- 

 eral, handling the ship where much reversing might be expected. 



Under these circumstances the resistances would be kept in on both motors. 

 The operation in this condition is very simple. To go ahead or astern on either 

 motor, simply close the "ahead" or "astern" switch; this requires about one-half 

 second for each motor. 



2. When it is desired to do economical cruising. 



This condition will arise after a certain amount of shiphandling has been done, 

 and both resistances will of course be in on the two motors ; it will be necessary to 

 cut the resistances out of the motors. This operation is not performed in answer 

 to a signal from the bridge, but is merely a change of cruising conditions. To 

 carry out this change, first open the field switch of the exciter; second, move the 

 control wheel of the turbine to "slow speed ;" third, move both short-circuiting levers 

 so as to short-circuit the rheostats ; fourth, close the exciter field switch ; fifth, bring 

 the turbine up to the desired speed. The total time required for these operations 

 is about thirty-five seconds; about twenty of these seconds are used up in waiting 

 for the field circuit of the generator to die out sufficiently to allow the short-cir- 

 cuiting levers to be moved. As has been previously stated, the short-circuiting 

 levers are locked by solenoids in series with the field of the generator. When the 

 exciter field switch is open the main field will, of course, die down and allow the 

 short-circuiting levers to be moved. 



3. When doing economical cruising, with resistances out of both motors, a 

 signal is received to back either one or both motors. 



First, open the "ahead" oil switches ; second, move the short-circuiting levers 



