408 



MOVING PICTURE APPARATUS 



[CH. XI 



connected to the line, and the secondary side is connected to the 

 arc lamp. (See Ch. XIII, 683, 739). 



The switches should be in a convenient location, so that the 

 current can be turned on or off without moving from the operating 

 position. 



As soon as the connections are made it is well to use an ammeter 

 and to find what current the arc will draw with the different set- 

 tings of the controlling lever of the rheostat or transformer. It is 



FIG. 226. MOVING PICTURE MECHANISM WITH OUTSIDE SHUTTER, O S. 

 For full explanation see Fig. 23 1 . 



a good thing also to use a voltmeter to determine the line voltage 

 on open circuit, also the voltage across the line, between the arc 

 terminals, across the rheostat or choke-coil, or if a transformer is 

 used, the voltage given by the secondary both on open circuit and 

 when the arc is running. The voltmeter or ammeter must be 

 designed for the kind and amount of current for which it is to be 

 used, that is, alternating or direct current. When a rectifier or a 

 motor-generator is used it will be necessary to have both direct 



