ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



119 



Abbe's Camera Lucida.* — Dr. L, Dippel describes an addition to 

 tbis apparatus f by wbicb drawing with bigb powers is much facili- 

 tated. Between the prism and tbe mirror are interposed two movable 

 glass plates of different tints, wbicb can be used together or separately 

 and serve to equalize tbe illumination of tbe field and tbe paper. 

 Dr, Dippel adds, " so far as my experiments go tbe modified instru- 

 ment surpasses all drawing instruments known to me in so bigb a 

 degree tbat it must come into very general use." 



Camerse Lucidae of Nobert and of Doyere and Milne-Edwards.t — 



We describe and illustrate tbese forms more as a " contribution to 

 tbe history of the camera lucida " than as offering any novelty 

 at the present day. In tbe form introduced by Nobert (fig. 14) 



Fig. 14. 



A is a rectangular prism and B a glass plate above the eye-piece, 

 inclined at an angle of 45°, and composed of thin glass to avoid 

 double reflection. Tbe arrangement is, however, of little use with 

 eye-pieces. 

 Tbe camera lucida of Doyere and Milne-Edwards (fig. 15) is 



Fig. 15. 



9 ' V 



I ii' 



included in the catalogues of most German opticians at the present 

 time, and has tbe advantage that it can be used with a bigb 

 magnifying power and with the strongest eye-pieces. Dr. L. Dippel 

 certifies that he has used it " almost exclusively for years, and can 



* Bot. Centralbl., xii. (1882) pp. 211-2. 



t See this Journal, ii. (1882) p. 261. 



X Dippel, L., 'Das Mikroskop und seine Anwendung,' 1867, pp. 232-3 (2 figs.). 



