TROUBLES WITH THE MAGIC LANTERN 



[On. I 



FIG. 30. ARRANGEMENT AND CENTERING OF THE RADIANT. 



(From the catalogue of Fuess). 



(/) The Radiant, i. e., the crater is too far to the right. 

 (2) The crater is too far to the left, 

 (j) The crater is too high. 



(4) The crater is too low. 



(5) The crater is too far from the lamp condenser. 

 (6-7) The crater is too near the condenser. 



(8) The crater is in the correct position. 



One of the condenser lenses may be cracked. If a new lens can- 

 not be inserted, but the cracked one must be used at the time, 

 rotate it around until the crack is least noticeable. 



There may be strings or wires hanging down in the path of the 

 beam of light. They will give sharp shadows on the screen. 

 Remove them. 



92. Defective or too opaque lantern slide. The lantern 

 slides may be cracked, producing a dark streak through the picture. 

 There may be dirt or mist on one or more of the glass surfaces. 



The slide may be too opaque. There is a tendency to make 

 lantern slides so opaque that only the most powerful radiants can 

 give anything like satisfactory screen images. This is a great 

 mistake. Lantern slides properly made arc very transparent and 

 show all the delicate shading, from the densest to pure transparency 

 (clear glass). Probably 99 slides are too dense where one is not 

 dense enough. The opacity of the slides made by the autochrome 



