TROUBLES WITH THE MAGIC LANTERN lCn. I 



FIG. 24. CARBONS IN BAD POSITION; THE UPPER CARBON CUTTING 



OFF THE LIGHT FROM THE UPPER PART OF THE CONDENSER, AND 



HENCE CASTING A SHADOW ON THE LOWER PART OF THE SCREEN. 



A Carbons at an inclination of about 25 degrees, with the upper or positive 

 carbon too far forward. 



B Carbons at right angles, with the upper carbon too far forward. 



S Screen image of the condenser face. As the upper carbon is in the way, 

 the upper part of the condenser is partly in shadow, and hence the screen image 

 will be shaded on its lower part due to the inverting action of the objective. 



FIG. 25. CARBONS IN BAD RELATIVE POSITION, THE LOWER OR NEGATIVE 

 CARBON EXTENDING UP IN FRONT OF THE POSITIVE CARBON. 



A Carbons at right angles, with the lower carbon too high. 



B Both carbons vertical, but the lower or negative one standing in front 

 of the upper one. 



.V Screen image of the condenser face. As the condenser is not well lighted 

 on its lower part due to the shading action by the lower carbon, the screen image 

 will be shaded correspondingly on its tipper part due to the inverting action of 

 the objective. 



