ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



107 



and drawings, giving the most elaborate and complete account that 

 perhaps has ever been given of any Microscope.* 



Prof. Lenhossek recommends the Polymicroscope especially for a 

 continuous series of objects. 



Dufet's Polarizing Microscope.|— This instrument (figs. 7-9) was 

 designed by M. H. Dufet to show the interference figures of crystalline 



Fig. 7 



fragments, and to allow of the accurate measurement of the axial angle 

 for different colours of the spectrum. G, fig. 7, is the plate of crystal 



Fig. 8. 



Fig. 9. 



which receives a pencil of convergent light polarized at P. The ravs 

 which traverse the objective H (No. 9 of Nachet) form at its principal 

 focus the real image of the isochromatic curves ; and these are examined 

 by a Microscope composed of the objective I (No. of Nachet), and of 



• Of. also ' Ein Polymikroskop von Dr. Joseph von Lenhossek,' 25 pp ' 1 nhot 

 and 2 pls.JJvo, Berlin, 1877 (from Virchow's Arch. f. Pathol. Anat, u. Physiol, £)! 



t Journ. de Physique, v. 

 (1886) pp. 275-81 (2 figs.). 



(1886) pp. 564-84. Bull. Soc. Franc, de Mineral., ix 



