ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 



249 



a' wheel-diaphragm. The adjustment is by sliding tube, and, after 

 adjustment, the tube may be fixed by a ring-clamp. A clip is attached 

 to one side of the stage to receive a sketch or label. The instrument 

 can also be fitted with an adjusting screw for focussing high-power 

 -objectives ; a condenser and iris-diaphragm are provided, if desired. 



Fig. 46. 



(2) Eye-pieces and Objectives. 



Leitz' Revolving Eye-pieces. — This class of fitting has only re- 

 cently been manufactured by the Wetzlar firm, who consider that their 

 design corrects many of the defects usually found in this accessory. 

 The lower lens (figs. 47 and 48) is so placed that it is permanently fixed, 

 the eye-lens of each combination alone moving in the revolver. So 

 accurate is the construction of the revolver, and so carefully are the 

 lenses adjusted, that the eye-pieces may be changed whilst a specimen 

 is in focus on the Microscope stage without a readjustment of the focus. 



April 18th, 1900 S 



