264 



PROJECTION MICROSCOPE 



[CH. IX a 



regardless of its size then the stage must be nearer the condenser and 

 a special substage condenser used to bring the cone of light from the 

 condenser to a focus more quickly where one employs high powers for 

 the projection. 



,L ''' A 3. \^^^ 



FIG. 210 



FIG. 210. Arrangement and Centering of the Radiant (Leiss}. 



In (/) The Radiant, i. e., the crater (Fig. 209) 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) 1 he 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. 



As pointed out in the explanation of Fig. 207, there may be a slight central 

 shadow with soft cored carbons when the lamp and condenser are in the best relative 

 position. 



If one wishes to make micro-projection a success it will be nec- 

 essary to give the apparatus the requisite time and thought. Try to 

 understand the conditions of success and continue experimenting until 

 you have learned to make it possible for the machine to do its best for 

 you. The satisfaction of showing a class real things is sufficient re- 

 ward for all the trouble. 



418. Screen and Screen Distance. For a screen nothing is 

 vSO good as a dead- white, smooth wall. A lusterless, white cloth 

 screen answers well also. It is an advantage to have this entirely 

 opaque, so that none of the light can pass through it. One must 

 remember that the light passing through the minute lenses of the 



