ZOOLOGY AND BOTAXY. MICROSCOPY. ETC. 



805 



instinmeut. It is also equally useful for photomicrography, as the 

 optical principle is based upon the system introduced by the late 

 Rev, T. W. Kingsley, but greatly improved in both optical and 

 mechanical effects. 



Fig. 101 will give an idea of the way in which the arrangement is 

 made, a paraffin lamp with 1/2 in. wick being the source of illumination 



Fig. 102. 



Fi<3. 103. 



for this purpose. " The instrument having been constructed by a 

 working man (an operative photogi-apher) v^^ho has devoted to it all his 

 leisure hours for a period of over ten years, it has been deemed only 

 fair that he should seek some remuneration for his labour, and he has 

 therefore secured his improvements to himself by a patent." * 



" A M AT EXJ K." — Notes on the Microscope Stand and some of its Accessories. III. 



The Microscope, IX. (1889) pp. 330-6. 

 Crisp, F. — Ancient Microscopes. Proc. Royal Institution, XII. (1889) p. 201. 



Seibert's Microscope. 



["By means of an improved Microscope made by Seibert of Wetzlar the 

 internal striu'ture of the antlirax bacillus can be made out. This consists of 

 a series of pearl-like corpuscles, which can be plainly seen to undergo 

 division. The magnifying power of the Microscope is said to be 2250 

 diametei-s."] Lcmcet, II. (1889) p. 887. 



(2) Eye-pieces and Objectives. 



1/10 in. Apochromatic Objective of NA- 1* 63.— Prof. Abbe has 

 designed, and Dr. Zeiss has produced a 1/10 in. apochromatic objective 

 of the large numerical aperture of 1 • 63, the limit hitherto reached having 

 been N.A. 1-60 in the case of an objective made by Mr. T. Powell. 

 Monobromide of naphthaline is used as the immersion fluid, and the 

 slides and cover-glass are made of flint glass. 



An immersion condenser of N.A. 1-60 has also been constructed by 

 Dr. Zeiss in order to secure approximately the full aperture of the 

 objective. 



Dr. H. van Heurck reports f that the objective allows of the 

 resolution of all known tests by axial illumination, and shows new 

 details in certain Bacteria. 



* Cf. Eng. Mech,, 1. (1889) pp. 242-3 (3 figs.), 

 t Bull. Soc. Belg. Micr., xv. (1889) pp. 69-71. 



