94 



SUMMARY OF CUKEENT RESEARCHES RELATING TO 



recesses in ores and rocks can be investigated without the interference of 

 shadows. The combination used consists of a triple achromatic system 

 giving an extremely large and flat field. 



i'lG. 5. 



Fig. G. 



Swift's Dissecting Lens.* — This special dissecting lens (fig. 6) 

 magnifies five times, and has a considerable working distance. 



Beck's Hand Demonstration Microscope.^ — This instrument (fig. 7) is 

 specially suitiible for lecture classes and demonstrations with mounted 

 specimens, and for examining unmounted specimens laid upon a table. 

 The plate of vulcanite which forms the basis of the instrument has clips 

 on both sides, the upper ones for holding a descriptive card, the lower 

 ones for holding the specimen. The lens which magnifies about seven 



Fig. 7. 



diameters and has a large field, is mounted in a screw jacket which gives 

 a large range of focusing motion. The lens-holder is mounted on three 

 pillars forming an unusually strong construction, and enables the instru- 

 ment to stand rough handling without damage. 



Steinach's New Microscope Stand.j — This stand, which was planned 

 by E. Steinach, and made by Carl Reichert, has now borne the test of a 



* Swift and Son's Catalogue, 1906, p. 68, fig. 110. 



t Zeitschr. wiss. Mikrosk., xxiii. (1906) pp. 308-12 (2 figs.). 



