ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 



237 



the exact fitting and working of the wearing parts, so as to secure per- 

 fection of alignment in the optical parts. When the Microscope is 

 used vertically, the stage is extremely rigid under manipulation even 

 with the highest objectives, and in this position the stage rests upon 

 the step-like supports of the pillars. The mirrors are mounted with 

 a swinging bar on an exceptionally strong focussed slide-bearing, the 

 swinging bar being provided with a " clock " for indicating central illumi- 



Fig. 25. , 



nation. For facilitating rapid work of a variable nature, such as occurs 

 in general medical work, a special and unique substage fitting (fig. 25) 

 can be supplied, the condenser being hinged to the mounting of the 

 upper dome-shaped iris diaphragm, so that it can be instantly swung 

 downwards, leaving this iris in situ, the distance of this diaphragm 

 from the stage being readily varied by the substage screw. The con- 

 denser can be immediately reinserted by a single movement without 

 disturbing the position of the instrument, and thus altering the lighting. 

 The mechanical stage can be attached or removed in a few 

 seconds, and is so constructed that it will always register to the 

 exact position it previously occupied, in order that an object can be 



