86 POLARIZED LIGHT AND ITS APPLICATION TO THE MICROSCOPE. 
Figure 50 shows a section of the analyzer consisting of a 
Nicol’s prism and its mounting, and protected like the polarizer 
by circles of thin glass. 
Fig. 60 . 
SECTION OF POLARIZER. 
SECTION OP ANALYZER. 
The mountings of the jpolariscojpe are made of different 
sizes, to suit both large and small microscopes, and the prices 
vary accordingly, depending principally upon the size and 
quality of the i^icol’s prisms employed. The largest and best 
Nicol’s prisms transmit the most light and are suited for the 
more delicate investigations. 
Some opticians place the analyzer above the eye-piece, but 
this arrangement diminishes the extent of the field. If the 
analyzing prism is small, and is placed just above the object- 
glass, it stops out a portion of the light, but if it is of sufficient 
size it transmits all the light from the object-glass, and does not 
in any manner limit the field of view. For these reasons we 
prefer mounting the analyzer in the body of the microscope 
just above the object-glass. It may also be adapted to the 
lower end of the draw-tube, which arrangement allows it to be 
rotated by the milled ring of the tube itself. 
111. A Touriiialiac plate fitted to the Eye-piece makes 
an excellent analyzer, when it can be obtained of suitable size 
and purity of color. Such tourmaline plates are compara- 
tively rare and costly. 
J. & W. GRUNOW & GO’S ILLUSTRATED 
