A. Kriiss, Hamburg. 



45 



Polarization Colorimeter. Original 



construction. (Fig. 5.) 



A peculiar combination of polarizing prisms with 

 a double quartz plate greatly increases the exactness 

 which is attainable with the colorimeter as ordinarily 

 constructed. For in this case not only the brightness 

 but also the colour of the illuminated halves of the 

 field have to be equalized. 



Browning's Pocket - Spectroscope with 

 A triple prisms. 



Browning's Pocket -Spectroscope, with 

 quintuple prisms. 



H. W. Vogel's Pocket - Spectroscope,. 



with mirror arrangement for comparison-spec- 

 trum, and with tube holder. 



H. W. Vogel's Pocket - Spectroscope, 



with universal stand, burner, bottles etc.; in case. 



Lummer and Brodhun's Photometer. (Fig. 6.) 



Fipr. 6. 



