Miscellaneous Implements Exhibited at Norunch, 1911. 255 



supplied with the plaiit should have a long life, as it is 

 always kept fully charged up. If only two or three 

 lights are being used, they are supplied from the batteries. 

 "When, however, more lamps are switched on, the extra current 

 demanded by the lamps actuates a relay. The current then 

 passes through the controller (which is an ordinary solenoid 

 starting switch) and is delivered to the dynamo. The dynamo 

 acts temporarily as a motor, and revolves the flywheel of the 

 engine until firing commences. The dynamo then supplies 

 current direct to the lamps, and also charges the battery to its 

 full capacity. In the event of a small number of lamps, in- 

 sufficient to start the plant, being kept on for a prolonged period. 



Fio. 3.— Electric Lighting Installation. 



undue depletion of the battery is guarded against by an 

 arrangement whereby the relay is actuated when the battery 

 voltage has reached a certain minimum. When all lamps are 

 switched off, and the battery is fully charged, the relay is 

 released and the plant automatically stops. The set consists of 

 a slow speed petrol engine or gas engine of Messrs. Lister's 

 standard design, the only addition being a simple exhaust 

 valve lift, worked by means of a solenoid on the controller 

 board, for easing the compression for starting and stopping, 

 a belt-driven shunt-wound dynamo, controller, and an 

 enamelled slate switchboard, on which is mounted the patent 

 relay, usual measuring instruments, and safety circuit-breaker. 



