an X-Ray Vacuum Spectrograph. 



495 



on the cone, consists of a slide F, that can be moved by 

 means of the screw H. On the slide the table N is placed, 

 that can be turned round the axis a with the aid of the 



Fisr. 1. 



^Y^^y-Y^- ■^ l „ A ••*•;■ ,- ._^^ ~^ 



screw h. This arrangement allows of a careful adjustment 

 of the crystal K. This is attached to the table by means of 

 a bow and two screws. The lower part of the cone is joined 

 to a metallic arm M, about 20 cm. long, with an index Z. 



