ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



523 



is given bj the arms EE, the effect being that the object-stage firmly 

 grips the Microscope- stage. An up-and-down movement is given by 

 the rack Rj,and Ro imparts a side-motion. Eacli guide-bar is graduated 

 and fitted with verniers to facilitate recording of the position of any 

 part of the preparation. The bracket K, regulated by a spring, holds 

 the ol^ject. 



Leitz' New Fine-adjustment.* — Messrs. E. Leitz have lately 

 fitted the Stand G H of their School Microscope, as well as their small 

 Stands J and K, with a very accurate, simple and ingenious l)all micro- 

 meter screw, whose operation will be understood from figs. 70 and 71. 



Fig. 70. 



Fig. 71. 



The movable piece which carries the Microscope tube with the rack-and- 

 pinion movements rests on a ball which slides up an inclined plane. A 

 spiral spring placed in the upper portion of this movable piece presses 

 against the ball and so obviates dead-way. A milled-head screw pushes 

 the ball and thus causes it to slide up the inclined plane. A micrometer 

 graduation can be applied to this milled head. 



Leitz Travelling Pocket Microscope. f — This Microscope (fig. 72) 

 consists of a half-round pillar with rectangular foot-plate, which is 

 clamped to the edge of the table or other similar place by means of a 

 cramp. The tube-carrier may be slid up and down the stand-pillar and 

 is secured in its proper position, when in use, by a set-screw. The 

 adjustment is effected by sliding the tube and by inclining the stage by 



* E. Leitz, Wetzlar : Special Catalogue (1913), Mikroskope, p. 22, 

 t Leitz Catalogue, 45a, p. 82. 



