A battery _r_, shown at Fig. 127, consists of any desired or requisite number of cells constructed and arranged in any suitable manner, and connected by proper conducting wires with the keyboard _s_. The latter is provided with a series of pole changers _s_^{ 1}, _s_^{ 2}, _s_^{ 3}, _s_^{ 4}, and switches _s_^{ 5}, _s_^{ 6}, and is shown in Fig. 128.
Each of these pole changers is arranged to effect and control one of the above-named operations, and is therefore connected with one of the aforesaid insulated wires forming the cable. For instance, the pole changer _s_^{ 1} effects the starting and stopping of the propelling engine; _s_^{ 2} controls the steering apparatus; _s_^{ 3} is connected with the steering index; _s_^{ 4} operates or adjusts the aforesaid guiding rods; and the switches _s_^{ 5}, _s_^{ 6} control and effect the firing of the charge in the magazine.
The connections between these pole changers and switches, and the apparatus they operate or control on board the boat, are as follows--that is to say, the said propelling engines have a throttle valve, which controls the admission of the gas from its generator or reservoir to the cylinders of the said engine, and in combination with this valve in the boat there is a shunt and set of electro magnets. The armature of the latter is connected with a lever, which is pivoted so that the action of the electric current in one direction through these magnets will pull one end of the said lever down, and the action of the current in the other direction will pull its other end down--that is to say, by reversing the current through these magnets the movement of the said lever is reversed; and this lever, connected by suitable means with the slide of the said throttle valve, will open or close the same, and thereby start or stop the engine as required.
For operating and controlling the above-described steering apparatus, and indicating the position of the rudder to the operator on shore, the following devices are employed, in combination with the pole changers _s_^{ 2}, _s_^{ 3} on the keyboard:--The pole changers are geared together by insulated toothed wheels, which are fixed on the spindles or axes of the said pole changers, so that the latter work accurately together and maintain the same relative positions to each other. The pole changer _s_^{ 2} is connected by one of the said insulated cable wires with a shunt on board the boat, which shunt is connected with a set of magnets arranged in combination with the valve of the engine that drives the steering apparatus, and which valve is reversed or opened and closed by the reversal of the currents through the said magnets, as above described, and the said engine moves the rudder to port or starboard at the will of the operator. In order that the operator may know the exact position of the rudder at any moment, a series of pins or projections fixed on an arc or other portion of the rudder stock, and arranged in combination with an insulated spring projecting into the path of the said series of pins, are employed. This spring is connected by one of the cable wires with the pole changer _s_^{ 3} on the keyboard, which is geared with and moves in unison with the pole changer _s_^{ 2}, so that the electric current that controls the steering engine, and the current that returns the indication of the rudder's position, will both be reversed simultaneously. A separate battery is connected with the index on the said keyboard, whereby a constant current is maintained between this index and the indicating apparatus on the boat.