VERTICAL ILLUMINATORS, METALLURGICAL MICROSCOPES 93 



downward through the objective into the prism V, the inclined 

 surface of which reflects the rays into a second right-angled re- 

 flecting prism attached to the end of the tube M. This latter 

 prism sends the rays to the eye through the ocular of the micro- 

 scope in the upper end of M. The entire tube M slides into a 



FIG. 44. Leitz Metallurgical Microscope fitted with Abbe Condenser 

 and Mirror. 



sleeve: by pulling out M, the prism attached to the lower end is 

 withdrawn from the path of the rays which then pass horizon- 

 tally through the tube N carrying at its end a projection eyepiece. 

 The image is thus formed upon the ground glass or photographic 

 plate of the camera. A pair of Hooke's keys K, K serve to 

 focus the image upon the ground glass. The rod r rising from 

 the stage serves to attach a mirror and an Abbe condenser. By 



