Franz Schmidt & Haensch, Berlin S. 



75 



e) Spectro-Photometer made according to Lu miner and Brod- 

 hun for the Imperial Physical and Technical Institute. 



Fig. 11. 



The apparatus is fitted with 2 collimators placed at right angles 

 to one another, provided with bilateral slits and micrometer screws. The 



observing telescope 

 S fiK lias an ocular slit. 



. J .i^.Ji^aBBL 



The apparatus is 



sufficiently sensi- 

 tive for the most 



exacting require- 

 ments. Further par- 

 ticulars may be ob- 

 tained from the re- 

 presentative of the 

 firm at the Exhi- 

 bition. (Fig. 11.) 



Fig. !_>. 



f) Helmholtz's Colour Mixing Apparatus, for mixing 2 to 4 

 different spectra of any intensity, with Rochon's prisms and bilateral 

 slits (vid. PL v. Helmholtz, ,,Handbuch cler Physiologischen Optik.") 



