1896.] 



MICROSCOPICAL JOURNAL. 



145 



sides of the tubes, with pins projecting from the body through 

 slits in the outer socket, and entering into spans in the arm 

 ends. The outer socket is also slit through its length in front, 

 to allow the fine movement bracket to pass through. We thus 

 have a semicircular bearing behind for the body-tube with two 

 elastic strips in front to keep it in place. 



This arangement brings the focussing milled heads and the 

 two of the stage movements conveniently close together. At 



first there was no intention of adopting a fine motion, but the 

 present one is simple and very effective. The bane of most fine 

 movements is tight fitting, which is particularly necessary when 

 the barbarous plan is adopted of raising the whole weight of the 

 body and its attachments to obtain this motion ; also a fine 

 motion is sometimes subject to derangement by the lever (if 

 such is used). The present fine motion consists of an inner 

 piece of tube carrying the object-glass, and fitted so loosely that 

 it easily drops out with its own weight ; its range is limited by 



