VERTICAL ILLUMINATORS, METALLURGICAL MICROSCOPES 103 
substage but is mounted upon a heavy base with central open¬ 
ing and provided with four large leveling screws. 
The third type of instrument is illustrated by the Leitz metal¬ 
lurgical microscope, Fig. 48. Here we have a compound micro¬ 
scope, consisting, as usual, of stage and substage, but with this 
difference, the tube and pillar are detachable from the stage, and 
the substage and support detachable from the base. By attach¬ 
ing the microscope and pillar to the base there is obtained a 
works microscope applicable to the study of large castings. The 
area of the casting to be studied is visible in the microscope in 
the opening between the legs of the horse shoe base. Light from 
a suitable radiant is deflected by 
the mirror m into a right-angled 
prism attached to the end of the 
illuminator. 
For the proper illumination of 
the objects, the methods and 
precautions already described on 
pages 78 to 82 are obviously 
equally applicable. 
Upright types of metallurgical 
microscopes are valuable not only 
in the study of polished and 
etched alloys but will be found 
convenient in the examination of 
opaque objects of all sorts, since 
in these instruments the construc¬ 
tion is such that the stage may 
be moved up or down for the, 
purpose of focusing the prepa¬ 
ration and thus the throwing out 
of the alignment of the illuminating rays from radiant to vertical 
illuminator is avoided. This arrangement of stage is most advan¬ 
tageous and may profitably be applied to chemical microscopes. 
Fig. 49 shows a well built metallurgical microscope of the 
vertical type having an unusually large stage with convenient 
and easily removable mechanical stage. 
Fig. 49. Spencer Lens Co. 
tallurgical Microscope. 
Me- 
