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SUMMARY OF CURRENT RESEARCHES RELATING TO 



through a clamping sleeve, he lengthened or shortened. The hinging 

 of the loup permits its adjustment in all positions. 



Fig. 15fi. 



(3) Illuminating- and other Apparatus. 



Seihert's Illuminating Apparatus. — This apparatus (fig. 157) is 

 of simple character and of special construction. The condenser has an 

 ap erture of 1 • 10. By the opening and closing of the iris-diaphragm 

 th e central illumination may be graduated as required. The oblique 

 il lumination is obtained by the adjustment of a mirror. 



Fig. 157. 



Fig. 158. 



Watson's Universal Condenser. — The object of Messrs. W. Watson 

 a nd Sons is to produce a condenser as suitable for low and medium as 

 for high-power objectives. The apparatus (fig. 158) has a total aper- 



