ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



297 



size). A is a brass plate having sliort angle- bearings at either 

 end sliding in the grooves B B and carrying at the lower end a ring 

 into which the objectives are screwed. A spiral spring C presses 

 down the plate A. The focussing is by means of the fine screw 

 worked by the milled head F, the point of which acts upon the 

 trigger-shaped lever D (attached to the side), which pushes against 

 the small metal disk E (mounted on A and rotating on a pinion to 



Fig. 43. 



Fig. 44. 



diminish friction) and this lifts up the slide A against the pressure of 

 the spiral spring above. The ring carrying the objective is quite 

 independent of the microscope-body, and should the slide A be found 

 to work too easily or the reverse, the bearings can be readily adjusted 

 by the capstan screw-heads shown at the side. 



An improved application of this fine adjustment has since been 

 devised, as shown in Fig. 44 ; the modification consisting of a wedge- 

 shaped lever worked by the fiuc-focussing screw (against a short 



