50 
Stands for erystallographie and 
petrologieal researches. 
Marhs 
A. Large Stand (Fig. 15). 
Similar to stands I and I" in form and size. 
Horse-shoe base; inclinable body. 
Coarse adjustment by rack and pinion G. 
Fine adjustment by means of micrometer screw with divided 
head M. 
Abbe illuminating apparatus, adjustable by rack and pinion 
W with condenser system C of 1.40 aperture mounted in sleeve 
and intercliangeable for cylinder diaphragm (M. 7. — ) or any of 
the apparatus No. 20 — 23. Diaphragm carrier with iris diaphragm, 
adapted for insertion of central stop diaphragms, mica and selenite 
films or polariser (Nicol) P; arranged to admit of rotation 
about the optic axis, of being placed obliquely and of being entirely 
swung out of the axis round the pivot f (vid. Fig. 1.5 and lO). 
Rotating stage with divided circle at circumfei'ence and cross- 
lines at right angles to one another. 
The d r a w - 1 u b e is provided with a mm-scale and separately 
adjustable by means of rack and pinion g and carries at its 
lower extremity an Amici (Bertrand) lens B, which may be in- 
serted through an opening in the outer tube ; at the upper end it 
is fitted with a divided circle for polariscopic measurements. The 
tube is provided at its lower end with Biot-Klein's quartz plate 
K and centering arrangement c c for the objectives. 
With condenser of 1.40 ap., iris diaphragm, polariser, analyser, 
Klein's quartz plate and Amici lens. 550. 
