62 



THE MICROSCOPE AND ITS REVELATIONS. 



ing 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; whilst the 'fine/ made by a milled-head at the back of 

 the ' limb/ raises or lowers the body by acting on the slide that carries 

 the rack-and-pinion movement. The body is furnished with a long 

 draw-tube, which carries a screw at its lower end for the reception of 

 objectives of foci too long to be worked from the nose of the outside body. 

 The stage, though thin enough to admit very oblique light, is very firm; 



Wale's New Working Microscope. 



it is circular, and has an all-round groove near its edge, alike on its upper 

 and its under side. Into this groove there fits a spring-clip for holding 

 down the slide upon the stage; and this may not only be turned round 

 into any position above the stage, but may be reversed so as to hold the 

 slide against its under side, thus enabling light of any degree of obliquity 

 to be thrown on the object. A removable 'Iris-diaphragm' ( 98), 

 which is made to open or close by a screw-action, is fitted into the stage 

 in such a manner that its aperture is very close to the under side of the 



