The Microscope in Section with the Images: i. 2, 3, Beams of light to the mirror; C 

 Image distance, i. e.: from eye-point, E-P, to virtual image (04); CD Condenser diaphragm; 

 EP Eye-point of ocular; Fj Upper focal plane of the objective; Fa Lower focal plane of the 

 eye-piece ; I y Mechanical tube-length, /. e. : from top of draw-tube to screw for insertion of 

 objective; Oj Object on the stage ; 62 Image formed by the objective were no field lens 

 present ; Os -.Image when field lens is present ; CU Virtual image ; A Optical tube-length, 

 i. e.: distance from the upper focal plane of the objective (Fj) to lower focal plane of eye- 

 piece F 2 . 



