ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



357 



The bellows and their stand, which are independent of the preceding, 

 are pushed up to the prism, thus giving a coarse adjustment. On this 

 movable bellows the author has set the ob- 

 jective-tube ; this is regulated by rack-and- 

 pinion and thus a fine adjustment obtained. 



The stand (fig. G7) possesses a heavy tripod 

 base, the rear foot C of which is rigid, the 

 two front ones S being levelling screws. The 

 pillar is a triangular guide-bar St bearing an 

 obliquely-toothed rack on its rear side and 

 centimetre graduations on one of the front 

 sides. At the upper end the bar is simply 

 truncated. The object-stage and prism-holder 

 are easily lifted off the bar over its upper end, 

 both being secured to sleeves worked up and 

 down by pinions engaging with the rackwork. 

 The stage is rotary and can be clamped by 

 screws ; it is made of blackened brass and 

 must be pierced by a large aperture to allow 



of the maximum amount of light being con- 



Fig. 68. 



Fig. 69. 



