USEFUL MICROSCOPE ACCESSORIES 



This idea was later elaborated by E. ten Siethoff 1 who combined 

 the hemisphere with a system of condensing lenses, thus permit- 

 ting not only the orientation of a crystal and its study under the 

 influence of plane polarized light sent through in the directions 

 of the different axes of vibration but also permitting observations 

 with strongly converging polarized light in different positions. 

 The apparatus consists of a condenser which is laid upon the stage 

 of the microscope, the diameter of its mounting being such as to 

 fit into the stage opening. The construction is shown in Fig. 60. 

 The crystal fragment is laid upon the flat surface of the glass 

 hemisphere S. 



FIG. 59. Robin Ball-and-socket Stage 

 for Metallurgical Microscopes. 



FIG. 60. ten Siethoff Glass Hemi- 

 sphere. 



FIG. 61. Klein Orienting Apparatus. 



Klein's Orienting Apparatus, 2 Fig. 61, consists of a glass cell C 

 to which a conical tube T is attached into which is ground a plug 



1 Central, f. Min., 1903, 657. 



2 Manufactured by Voight and Hochgesang, Gottingen, Germany. 



