METALLOGRAPHY 199 



specially designed metallurgical stands (Fig. 64). It 

 shows the general principles which guide the construction 

 of these instruments, but has many special features in 

 design, such as the massive foot and limb, which give 

 great stability in any position. The coarse and fine 

 adjustments both actuate the stage. The various illumi- 

 nating appliances used in metallography are carried in 

 dovetailed slides on the body. Of these, the iris diaphragm 

 is shown in position, the cover-glass and parabolic 

 reflectors at the side. The camera used with metal- 

 lurgical microscopes may be either vertical or horizontal, 

 but there are microscopes, the Marten's stand made by 

 Zeiss for instance, which work only in a horizontal 

 position. 



Adaptation of Ordinary Microscopes to Micro-metal- 

 lography. Fig. 65 shows how an ordinary microscope may 



Fig. 65 



ARRANGEMENT OF CAMERA FOR MICRO-METALLOGRAPHY 



be adapted for photomicrography of metal surfaces. A 

 word may be given to the camera itself, which was built 

 at home, and is another example of easily made appara- 

 tus. It is of half -plate size, of very long bellows extension, 

 and carried on two pieces of nickel-plated bicycle tubing. 

 The door at the side can be opened to focus on a piece of 

 card placed in the camera back. Stands for the micro- 



