THE FINE ADJUSTMENT 



169 



fact the object holder can be made to receive, and the optical appa- 

 ratus arranged to examine, preparations of almost any required size. 

 To accomplish this H (fig. 128) is made hollow, and in place of 

 the usual triangular ' conductor' of the fine adjustment, a swallow- 

 tail-shaped slide F (figs. 129, 130) is placed, the upper part of which 

 is hollowed out to receive the spiral spring U (fig. 129). The lower 

 part of this is also hollowed and conceals the long box which receives 



A. A_ 



Fiu. 130 (1898). 



the micrometer screw M (fig. 129). The pressure of the spiral 

 spring is in the direction of the axis of the micrometer screw, which 

 works against a hardened point shown at D 2 fixed on the dust-tight 

 under-cover of H (fig. 128). This < conducting slide ' F (fig. 129) 

 is firmly screwed to the part carrying the coarse adjustment, and the 

 aluminium tube T is connected in the usual manner with therackwork. 

 To avoid what appears to have been considered a peril in the 

 exposure of the milled head carrying the fine adjustment screw in the 

 usual form of the 

 Zeiss stand, Dr. 

 Czapski caused the 

 fine adjustment to 

 be placed in the 

 hollow of the up- 

 right H (fig. 128), 

 so that the screw 

 itself is complete- 

 ly removed from 

 1 1 i rect contact with 

 the hand ; the 

 turning of the 

 ' micrometer ' or 



PIG. 131. Reichert's new patent lever fine adjustment j 1899). 



fine adjustment screw only takes place by means of the motion of 

 the small milled heads W W (figs. 128 and 130) which work the 

 endless screw E (fig. 130). This engages the wheel S, which being- 

 fastened on to the flange of the fine adjustment screw, replaces or 



