VERTICAL ILLUMINATORS, METALLURGICAL MICROSCOPES 101 
struction of the prism chamber both of which now permit easy 
cleaning of the glass surfaces. In the older models the removal 
of dust and dirt from the glass surfaces was almost impossible. 
Metallurgical Microscopes for the Examination of Large 
Castings, etc., are now manufactured by a number of different 
firms. Such instruments are often designated, as “Works 
Microscopes,” since their purpose is 
the study of materials of construction 
already in place or too large to bring 
into the laboratory. 
Fig. 46. Stead Works Micro¬ 
scope. 
Fig. 47. Tassin Metallurgical Microscope. 
As indicated by the name and purpose they are compact, sub¬ 
stantially built and easily transportable. They consist essen¬ 
tially of a compound microscope, whose pillar or handle arm fias 
been separated from the remainder of the instrument in a line 
in the plane of the stage, and attached to a suitable base or to 
three legs. In other words, these instruments are microscopes 
without stage or substage. When in use, the base rests upon 
the object to be studied and the tube carrying objective, illumi¬ 
nator and ocular is racked down until the surface of the object 
