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1900.) MARINE REVIEW. 23 ancing wire and the fields of the exciter. This current is multiplied in the manner indicated above and power is transmitted to the rudder motor, thus causing the motor to turn the rudder. The rudder will continue to move until the sweep of the rudder column is.,moved to a position corresponding with the position of the sweep of the steering column, when current -will cease to flow in the balancing wire and the generator and rudder motor will cease to function. The rudder will therefore assume a position corresponding with the sweep of the steering column. During this time tle motor driving the generator and exciter has had to do work proportional to the power required of the generator and also a slight amount of work necessary to rotate the two armatures. When current ceases to flow through the balancing wire no power is required except the friction load of driving the generator and exciter armatures in dead fields. This power is, of course, very small. The method of multi- plying the effect of the current in the balancing wire makes it possible to Fig. 6. Separately-driven exciter. use very small currents in the resistances, these currents being about two amperes each, not enough to operate four incandescent lamps. That the man at the wheel may always know how the rudder is re- sponding to his wheel, a rudder indicator. is mounted on or near the steering column. The column illustrated in Fig. 3 shows the indicator mounted upon it. A second divided resistance is located on the rudder column and the movement of the rudder shifts the sweeps of both re- sistances simultaneously. A very small current through the second re- sistance is transmitted to the indicator and moves the pointer of the indicator to correspond with the movement of the rudder. The scale of the indicator is indexed so that the pointer moves one degree on the scale for each degree of arc of the rudder and the pointer and rudder at all times correspond in position. PECULIAR ADVANTAGES OF THE SYSTEM. The speed of a motor depends upon the voltage. If the wheel. is turned rapidly, current at a relatively high voltage- is. delivered -to the motor and the motor moves quickly, turning the rudder quickly. If the hand wheel is moved slowly it starts action slowly in the exciter and generator, and the rudder motor will move slowly. It will thus be seen that the control of the rudder is just as exact as if the hand wheel were connected directly to it. It was no small task to design motors and: dynamos capable of functioning so exactly as this and capable of being Fig. 7. Rudder motor. suddenly reversed under varying currents. It is one of those things which look simple after some one has shown how to do them. . The motor of the steering gear can be reversed from full speed in one direc- tion to full speed in the other direction in about four seconds. All electric circuits are constantly closed, consequently there is no sparking in any part of the gear or controlling apparatus. Dynamos are ordinarily located in a room close to the boilers. The generator for the steering gear is operated by the same man who operates the lighting machines. When designing equipments for new vessels the company re- commends a consolidation of all generating apparatus for lighting and power, including the steering equipment. Wires can be run through water-tight bulkheads with much greater facility than can steam pipes and may easily be bent any number of times. These wires cost less than hall the price of copper steam pipes ordinarily used for steering engines. The system is silent, and being well balanced does not cause any vibration to the ship. The use of the electric steering gear does away with heat and therefore increases the value of large spaces in' the ship, both for cabins and for cargo. The simple nature of the apparatus used reduces to a minimum any possibility that it will get out of repair. No adjustments have to be made after the apparatus is set up.' It can there- fore be installed by any intelligent electrician. The working currents are in short and well-protected mains. The controlling currents are very Fig. 8. Kngine-driven generator. small, and none of the currents necessary can possibly affect the navigat- ing instruments of the ship. Only five small wires (including the rudder indicator wires) are car- ried to the steering column. It is thus feasible to establish a number of stations on the ship from which the rudder can be operated. A steering column at any one of these stations can be placed in service by changing ae Fig. 9. Rudder motor and auxiliary steering column on Russian Cruiser Variag. a simple switch in the dynamo room. This is a point of special im~- portance for ships of the navy. The accompanying cut (Fig. 9) shows an auxiliary steering column located in the stern of the Variag near the motor controlling the rudder. The rudder can be operated from this controlling stand or from the wheel house, as desired. Provision is made, however, so that the rudder cannot