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. 40. Spencer Lens Co. Me- 

 tallurgical Microscope. 



