516 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



slips of rock-crystal or of ultra-violet transparent glass. The makers 

 give warning that the monochromats cannot be used with daylight ; and 

 also that immersion-fluids of other composition, unless they have the 

 same refractive index, cannot be used for ultra-violet photomicrography. 

 For projection of the image on the photographic plate a special series of 

 rock-crystal oculars has also been constructed. The ocular number gives, 

 as in the case of the compensation oculars, the angular magnification. 



K„ P.. 



, i ii i i i 



V L <ap A ) 



p. 



K, 



Off 



J> 



Fig. 111. 



Zeiss' vertical camera is used as the photographic apparatus, because the 

 perpendicular position offers various advantages over the horizontal. 

 This is shown in fig. 109, about one-sixth of the full size. S x is the 

 screw for firmly receiving the foot-plate for the Microscope ; P is the 

 rock-crystal reflexion prism, which reflects the horizontally incident light 

 along the axis of the Microscope ; S^ is a plane mirror for observing 

 the spark image on the uranium glass ; I) a diaphragm carrier with 

 inserted uranium glass-plate swung aside. The upper arrangements are 

 shown more clearly in fig. 110, which is also one-sixth of full size. B is 

 the foot of the vertical camera ; S 2 a clamp-screw for securing the 

 rotatory graduated pillar S t ; H the adjustable sleeve for the " finder " 



