CH. I] 



MAGIC LANTERN WITH DIRECT CURRENT 



tioned above ( 16) will avoid this; and furthermore, the operator 

 should start the arc lamp before the lecturer turns off the room 

 lights ( 25). 



34. When to put the lamp out. The operator should not turn 

 out the arc lamp until the lecturer turns on the room lights. The 

 intervals of total darkness so common in exhibitions can be avoided 

 by keeping in mind the suggestions in this and the previous section. 



It is also a good plan for the operator to remove the last slide 

 when the lecturer is through with it, and show a blank disc of light. 

 This will inform the lecturer that all the slides have been exhibited 

 and give him the hint to turn on the room lights. 



To determine how a lantern slide 

 should be placed in the carrier to give 

 an erect image on the screen : 



Look through the lantern slide toward 

 something light. Turn it until the 

 picture is right side up and the print 

 reads right, as in this model. 



Then turn the slide so that the bottom 

 edge is uppermost like the next model. 



FIG. 7. STANDARD AMERICAN LANTERN SLIDE, FULL SIZE, WITH 

 DIRECTIONS FOR INSERTING IT IN THE CARRIER so THAT 

 THE SCREEN IMAGE WILL BE ERECT. 



