32 



Here also the iris-diaphragm of the illuminating apparatus regulates the 

 aperture. 



Price in case: Marks wo. . Code-word: Paquira. 



The achromatic condensers specified under 8 10 slip from above into 

 the sleeve of the illuminating apparatus, which must therefore be completely racked 

 downwards before inserting the condenser system (see Fig. 11). 



These condensers cannot be tised on the large Mineralogical Stand l b , or 

 on Stands II a and IV a , excepting in their inclined position. 



11. * Centring Apparatus for Microscope Objectives which are to be 

 used as condensers. No. 32. Fig. 11 f. 



Price: Marks 12. . Code-word: Parabanda. 



In many instances it appears desirable to use achromatic, or also apochromatic, ob- 

 jectives as illuminators instead of the condensers specified above. For this purpose we 

 supply a sliding sleeve with centring collar into which such objectives may be screwed and 

 which fits into the sleeve of the illuminating apparatus. 



12. HARTNACK'S Illuminating Apparatus for monochromatic light, 



No. 33. 



The spectrum projected by this apparatus into the plane of the object is 

 sufficiently extended to ensure approximately uniform monochromatic illumination 

 of the field with high magnifications. 



Ft ice in case: Marks 120. . Code-word: Paradero. 



13. * ENGELMANN'S Micro-spectral Objective, No. 34, for observing the 



effect of individual colours of the spectrum upon microscopical objects (see "Bot. 

 Zeitung", vol. XL, 1882, pp. 419426; also "PFLUGER'S Archiv f. d. ges. Phy- 

 siol.", vol. XXVII, 1882, pp. 485490.) 



Price in case: Marks 160. . Code-word: Paradigma. 



14. *ROLLETT'S Spectro-Polariser, as modified by DIPPEL, No. 35, for 

 determining the character and degree of double refraction in microscopical ob- 

 jects (see "Zeitschrift f. Instrumentenkunde", vol. I, 1881, p. 366372 and DIPPEL, 

 loc. cit, p. 619.) 



With selinite films for red of the II. and III. order. 

 Price in case: Marks 200. . Code-word: Paradura. 



The apparatus specified under 12 14 can only be used on Stands ll a and 

 IV a in their inclined position. 



Special Centring Collar, No. 36, for Nos. 12 14. 

 Price: Marks 6. . Code-word: Parafraste. 



We shall be pleased to send to applicants detailed particulars of the appa- 

 ratus (specified above under 12 14) for spectroscopically decomposed light. 



