436 TROUBLES WITH MOVING PICTURES [Cn. XI 



The automatic magic lanterns are devised to show automatically 

 a series of ordinary lantern slides. One of these instruments is 

 called the "Advertigraph" by Williams, Brown & Earle and has a 

 capacity of 24 lantern slides. Another form, designated a 

 "Stereomotorgraph" by the Charles Besler Co., has a capacity 

 of 52 lantern slides. These instruments are very effective for 

 advertising and for exhibitions in museums. 



TROUBLES 



599. There are two main troubles confronting the moving 

 picture operator: A poor screen image, and fire in the operating 

 room. 



A poor screen image. This may be due to any one or a combina- 

 tion of the following: 



(1) An operator with insufficient knowledge and experience. 

 This is probably the most common cause. 



( 2 ) A poor pro j ection apparatus . 



(3) A bad light due to insufficient current or to a wrong relative 

 position of the carbons. 



(4) The parts of the projection apparatus not on one axis. 



(5) The film may be poor; too dark or not sharp, or worn out, 

 or badly perforated, or scratched, giving rainstorm appearances. 



(6) The film may be wrong side up or wrong side out in the 

 machine. 



(7) There may be a "misframe" ( 584, 597). 



(8) The apparatus or the floor may vibrate, giving a jerky 

 appearance on the screen. 



(9) The shutter may not be in the right position or of the right 

 design, hence flicker, travel ghost, etc. 



(10) The general light in the room may be too great, hence, a 

 gray picture without sufficient contrast. The same effect is pro- 

 duced by a single room light or the light from a door or window 

 shining directly on the screen. 



Fire in the operating room. This seems inexcusable, but may 

 occur. To avoid loss of life and of property the operating room 

 must be (i) truly fire-proof; (2) it must have a large flue leading 



