2O2 



TABLES 21 9, 219A. 

 TRANSMISSIBILITY OF RADIATION, 



TABLE 219. Color Screens. Jena Glasses. 



See " 0ber Farbglaser fiir wissenschaftliche und technische Zwecke," by Zsigmondy, Z. fur In- 

 strumentenkunde, 21, 1901 (from which the above table is taken), and " Cber Jenenser Licht- 

 filter," by Grebe, same volume. 

 (The following notes are quoted from Everett's translation of the above in the English edition of 



Hovestadt's " Jena Glass.") 

 Division of the spectrum into complementary colors : 



ist by 2728 (deep red) and 2742 (blue, like copper sulphate). 

 2nd by 454 (bright yellow) and 447 111 (blue, like cobalt glass). 

 3rd by 433 m (greenish-yellow) and 424'" (blue). 

 Thicknesses necessary in above : 2728, 1.6-1.7 mm. ; 2742,5; 454 IU , 16; 447, 1.5-2.0; 433'", 



2.5-3.5; 424 m , 3 mm. 



Three-fold division into red, green and blue (with violet) : 

 2728, 1.7 mm. ; 4i4 m , 10 mm.; 447 m , 1.5 mm., or by 

 2728, 1.7 mm. ; 436"', 2.6mm. ; 447'", 1.8 mm. 



Grebe found the three following glasses specially suited for the additive methods of three-color 

 projection : 



2745, red ; 438 m , green; 447, blue violet ; 



corresponding closely to Young's three elementary color sensations. 

 Most of the Jena glasses can be supplied to order, but the absorption bands vary somewhat in 



different meltings. 

 See also "Atlas of Absorption Spectra," Uhler and Wood, Carnegie Institution Publications, 1907. 



TABLE 2 19a.- Water Vapor. 

 Values of a in I = I e ad , d in c. m. I ; I, intensity before and after transmission. 



First 9; Kreusler, Drud. Ann. 6, 1901,; next Ewan, Proc. R. Soc. 57, 1894, Aschkinass, Wied Ann. 55, 1895; ^ ast 3i 



Nichols, Phys. Rev. i, i. 

 See Rubens, Ladenburg. Verb. D. Phys. Ges. 1911, for extinction coefs., reflective power and index of refraction, i jx 



to 18 /x. 



SMITHSONIAN TABLES. 



