266 Tables 313-316. 



STANDARD WAVE-LENGTHS. 



TABLE 313. — Absolute Wave-length ♦ of Red Cadmium Line in Air, 760 mm. 



Pressure, 15' 0. 



6438.4722 Michelson, Travaux et Mem. du Bur. intern, des Poids et Mesures, 1 1, 1895. 

 643S.4700 Michelson, corrected by Benoit, Fabry, Perot, C. R. 144, 1082, 1907. 

 6438.4696 (accepted primary standard) Benoit, Fabry, Perot, C. R. 144, 1082, 1907. 

 * Id Angstroms. 10 Angstroms = i mju. = lo-c mm. 



TABLE 314. — International Secondary Standards. Iron Arc Lines In Angstroms. 



Adopted as secondary standards at the International Union for Cooperation in Solar Research 

 (transactions, 1910), Means of measures of Fabry-Buisson (i), Pfund (2), and Eversheim (3). Re- 

 ferred to primary standard = Cd. line, \ = 6438.4696 Angstroms (serving to define an Angstrom). 

 7j5o mm., 15° C. Iron rods, 7 mm. diam. length of arc, 6 mm.; 6 amp. for A greater than 4000 

 Angstroms, 4 amp. for lesser wave-lengths ; continuous current, -j- pole above the — , 220 volts ; 

 source of light, 2 mm. at arc's center. Lines adopted in 1910. 



TABLE 315. — International Secondary Standards. Iron Arc Lines in Angstroms. 

 Adopted in 1913. (4) Means of measures of Fabry-Buisson, Pfund, Burns and Eversheim. 



(i) Astrophysical Journal, 28, p. 169, 1908; (2) Ditto, 28, p. 197, 1908; (3) Annalen der Physik, 30, 

 p.815, 1909. See also Eversheim, ii>id. 36, p. 1071, 1911 ; Buisson et Fabry, Hid, 38, p. 245, 1912} 

 (4) Astrophysical Journal, 39, p. 93, 1914. 



TABLE 316. — Neon "Wave-Lengths. 



International Units (Angstroms). Burns, Meggers, Merrill, Bull. Bur. Stds. 14, 765, 1918. 

 »MiTHsoNiAN Tables. 



