502 



SUMMARY OF CUKIIKNT RESEARCHES RELATING TO 



Leitz' Camera Ocular.* — This auxiliary apparatus (scries No. 98) is 

 shown in fig. 92. The distinction between this and other forms of such 

 apparatus made by the Wetzlar firm, is that the drawing plane lies 

 horizontally on the work-table directly in front of the observer. This 



Fig. 92. 



is effected by inclining the Microscope at an angle of 45°, and by em- 

 ploying a somewhat changed form of prism. The diminution of the 

 light is attained by the use of two neutral-tinted glass discs set in 

 movable arms. 



Blakeslet, T. H. — Single-piece Lenses. 



Proc. Phys. Soc, London, xviii. (1903) p. 591. 

 Conbadt, A. E. — On the Chromatic Correction of Object-glasses. 



Monthly Not. Boy. Astron. Soc, lxix. (1904) p. 274. 

 Fery, Ch. — Methode nouvelle pour la Determination des Constantes des Lentilles. 



Bull. Soc. Franc, de Phys., 1903. p. 226. 

 Spitta, E. J. — Improvements in Modern Objectives for the Microscope Popularly 

 Explained. 



[The author reviews the chief defects of lenses, and shows how Jena glass is 



adapted to neutralise them. He emphasises Abbe's labours in this field.] 



President'* Address. Journ. Quekett Micr. Club. Feb. 1905. 



pp. 141-52 (2 pis.. 12 figs.). 

 Trozewitsch, S. E. — Anfertigung von Objecktiven fur Teleskope, Mikroskope 



nnd Photographische Apparate, die Optische Technik 

 der Mikroskope und Teleskope (Russisch). 



Warsaw (1903) 322 pp. 

 „ „ Zur Frage uber das Apian atische System. 



Zeits.f. Math. u. Phys., li., (1904) p. 100. 



(3) Illuminating and other Apparatus. 



Leitz' Apparatus for Observation of Ultra-Microscopical Par- 

 ticles.! — This apparatus is shown in fig. 93. It consists of a plate 

 applied to the object-stage and clamped to the pillar. This plate con- 

 tains a small chamber through which, by means of an india-rubber tube, 

 the liquid for examination is conducted. The rate of flow is controlled 

 by a stop-cock, and a small window admits light into the chamber. 

 The fluid may be observed bare or protected with a cover-glass. The 



* Catalogue No. 41 (Mikroskope) 1905, p. 80. t Tom. cit., pp. 66-67. 



