518 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tube is movable in the body-tube by rack and pinion g, and has a milli- 
metre division giving the total tube-length. The eye-piece, which is 
provided with cross wires, is placed in the draw-tube from above. 
Above the eye-piece the analyser A (Hartnack-Prazmowski prism) is 
Fig. 55. 
applied, the mounting of which carries an index showing the orientation 
of the analyser on the divided circle T. 
For observing the optic axial figures in convergent light, an Amici 
auxiliary objective can be applied by the knob B through an opening in 
the outer tube, and fitted into a slot at the lower end of the draw-tube. 
The eye-piece forms with this objective an observing Microscope, 
