CH. XI] MOVING PICTURE APPARATUS 401 



supplying the power. Some power companies object to the use of 

 an inductor (choke-coil). In such cases a transformer can be used 

 instead. 



563. Stand or table. A stand or table is provided by the 

 makers of the machine. The method used to set up the stand will 

 be fairly obvious from the illustrations furnished by the makers of 

 the particular machine used. Generally this stand is made of 

 brass tubes. One maker provides a heavy iron pillar. With this 

 make provision must be made to anchor this pillar firmly to the 

 floor. 



If the machine is to be installed permanently, it is often better to 

 use a stand constructed of concrete or a very heavy wooden table 

 instead of the light stand regularly supplied. A very slight motion 

 of a rickety stand will cause an enormous movement of the picture 

 on a screen 15 to 30 meters (50 to 100 feet) away. 



564. Unpacking. The moving picture machines coming from 

 the factory are very carefully packed. When removed from the 

 box, it is advisable to take careful notes of just how the different 

 parts are packed and to number the wooden cleats used to hold 

 things in place, especially if the machine will need to be shipped 

 away again. 



Be careful in unpacking all parts, especially the lenses. Do not 

 throw away any wrapping material until sure that no parts are 

 missing. 



565. The moving picture machine. When unpacked the 

 moving picture machine will be found to consist of a stand and base- 

 board, arc lamp, lamp-house, condenser, aperture plate, objective, 

 shutter, film magazines, and mechanism for moving the film. 

 There will also be an extra film reel and a rewinder (fig. 221-224). 



566. The arc lamp. The arc lamp usually supplied with 

 moving picture outfits is of the hand-feed type with inclined car- 

 bons. The handles for feeding the carbons and for slight up and 

 down adjustments project backwards so they may be manipulated 

 without opening the lamp-house. The good makes of arc lamp are 

 adjustable so that the carbons can be held in the vertical or the 



