CH. I] DO AND DO NOT WITH THE MAGIC LANTERN 



8. Open the switch before 

 inserting or changing carbons. 



9. Center the parts of the 

 lantern when it is first installed 

 ( 51-60). 



10. When the condenser and 

 objective are once centered they 

 should be fixed in position 



8. Do not try to insert car- 

 bons when the current is on. 

 Open the switch. 



9-10. After the parts of the 

 lantern are once centered, never 

 change the position of the con- 

 denser or objective for center- 

 ing: . 



1 1 . Use the fine adjustments 

 on the arc lamp (fig. 3) for cen- 

 tering the light on the screen 

 after the first centering. Look 

 at the carbons through the 

 lamp-house window occasionally 

 to make sure that they arc in 

 the correct relative position 

 ( 79). 



12. Make sure that the arc 

 lamp and condenser, the con- 

 denser and objective are separ- 

 ated the right distance ( 55- 

 56). 



13. For the triple condenser 

 select a condenser lens to go 

 next the lantern slide which 

 shall be of approximately the 

 same focus as the projection 

 objective, then the light from 

 the condenser will cross at the 

 center of the objective (fig. 1-2). 



ii. Do not fail to keep the 

 light centered by the use of the 

 fine adjustments on the lamp 

 and by keeping the carbons in 

 the correct relative position. 



12. Do not try to use the 

 lantern when the arc lamp and 

 condenser are too near together 

 or too far apart. 



The same for the condenser 

 and objective. 



13. Do not try to use an 

 objective with a condenser that 

 does not cross its rays at the 

 center of the objective. Objec- 

 tive and condenser should have 

 the same focal length approxi- 

 mately. 



