135,922. Read, H. J., and Bransom, W. J. Dec. 2, 1918. Systems of charging galvanic batteries.-In a supply plant consisting of a prime-mover, generator, and battery, the charging of which is under the control of an electrolytic meter, the meter controls the ignition circuit and throttle valve of the engine and an engine turning-gear so that the generation is automatically started and stopped according to the condition of the battery. One electrode f of the meter is balanced by a spring k and, according to its weight, either opens or closes the ignition circuit &c. In a modification, the variation in weight of both electrodes is used to energize two oppositely-acting solenoids alternately and throw over a switch for the same purpose. The action of the electrode may be direct or through relays on the switch. The relay devices and frames described in Specification 22348/13 mav be used with the electrolytic meter. The switching-devices may cause the engine to start on petrol and run on paraffin.