31 



-r 



Fig. 11. 



Showing the ABBE Illuminating 

 Apparatus with cylinder - diaphragm, 

 various condensers and the centring 

 apparatus for objectives. 



r: screw for clamping the condenser 

 in the sliding sleeve; p: knob of iris- 

 diaphragm; u and ti : centring screws; 

 s: mechanism for elevating and depress- 

 ing the illuminating apparatus. 



