ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



639 



Pillischer's New Model " Kosmos."* — This instrument (fig. 142) 

 has the following features : a substantial solid and firm stand, having 

 rack-and-pinion course adjustment ; micrometer screw fine adjustment ; 

 substage with centring screws and rack-and-pinion focusing adjust- 

 ment ; new form of sliding pinhole diaphragm and iris diaphragm ; two 

 eye-pieces ; f, \ and ^ objectives ; and Abbe condenser 1 " 20 N.A. 



Microscope specially adapted for Mineralogical Investigations at 

 High Temperatures.f — E. Sommerfeldt has designed this instrument to 

 meet the difficulties felt in applying heating chambers to mineralogical 

 Microscopes, as it is usually found that such chambers interfere with the 

 rotatory arrangements of the Microscope. C. Leiss has, it is true, made 

 some models intended to overcome the difficulty, but at the disadvantage 

 of complications. E. Sommerfeldt, therefore, aims at simplicity. x n 



Fig. 143. 



his apparatus, fig. 143, the same rotation axis and the same divided circle 

 suffice for the rotation of both object-stage and Nicol prisms. The 

 rotatory object-stage consists of a strong divided circle, which is sur- 

 rounded by a ring R carrying the vernier, while perpendicularly to its 

 object plane the ring carries a rod S, to one of whose ends is attached a 

 rack-and-pinion movement for the polariser N, and the other, by means 

 of an adjustable cross-rod, grips the ocular collar at Si ; this arrange- 

 ment makes possible a rotation of object-stage and polariser about the 

 axis of the instrument. In order to follow the movement of the tube 

 during the adjustment, either the screw S x or the screw S 2 , which move 

 along grooves, should be loosened. For measurement of angles of rota- 

 tion, these screws are naturally clamped. The rod S and cross-rod Q can, 



* Catalogue Optical Convention, 1905, p. 11G, fig. 25. 

 t Zeitschr. wiss. Mikrosk., xxi. (1904) pp. 181-5 (1 fig.). 



2 U 2 



