ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



703 



Plossl's Large Stand. — This instrument (fig. 128) has a coarse 

 adjustment of unusual construction, which is claimed to be eminently- 

 simple and to work very smoothly and surely, much better than rack 

 and pinion. 



Each of the two milled heads, 48 mm. in diameter, has near its 



Fig. 128. 



periphery a steel pin, to which is attached, so as to be movable, one 

 end of a short rod. The latter is similarly movable at its other end 

 on a pin on the body-tube, which moves in a rectangular slot 35 mm. 

 long, cut parallel to the optic axis in the outer tube, lined with cloth, 

 in which the body-tube slides. The result of the arrangement is, that 

 on turning the milled heads the body-tube is correspondingly raised 

 or depressed. 



3 A 2 



