54 THE MICROSCOPE AND ITS REVELATIONS. 



39 very suitable to such requirements. It is solidly built, without being 

 unduly weighty, carries a body of full diameter (which can be lengthen- 

 ed by a draw-tube to ten inches), and stands well upon its base. The 

 6 coarse ' adjustment is made (as in the preceding case) by sliding the body 

 within the tube that grasps it, the lining of which with cloth makes it work 

 very easily (Fig. 39); but a rack and pinion movement may be added at a 



JttCL 



Parkes's Educational Microscope. 



small additional cost. The ' fine ' adjustment is made by a screw (turned 

 by the milled-head at the top of the vertical pillar), which acts on the car- 

 riage of the body; and as this carriage slides between dove-tailed grooves, 

 the adjustment is made with entire freedom from ( twist.' The Microscope 

 is furnished with two eye-pieces, of which the lower is preferable for objects 

 requiring good definition; whilst the higher gives a flat field of eight inches 



