226 THE HISTOKY AND DEVELOPMENT OF THE MICROSCOPE 



are drawn together by a screw, which thus regulates the pressure 

 made by the two ridges that work into the two grooves on the limb. 

 When this pressure is moderate, nothing can be more satisfactory 

 than either the smoothness of the inclining movement or the 

 balancing of the instrument in all positions; while, by a slight 



FIG. 180. Swift's improved ' Wale's ' microscope (1881 and 1883). 



tightening of the screw, it can be firmly fixed either horizontally, 

 vertically, or at any inclination. The ' coarse ' adjustment is made 

 by a smooth-working rack ; the fine adjustment is Swift's patent 

 described on p. 172 (fig. 135), and the attachable mechanical stage of 

 this firm can be readily added (as in fig. 180), but in the best and 



