Wave-Length Standards in the Spectra of Carbon and Tin in the Schumann Region

Abstract
In the region 2000 to 1500A the strong lines of C I and Sn II have been measured to about 0.02A by direct comparison with iron. The dispersion of the second order lines was 3A per mm and the carbon groups were well resolved. The 1930.93 line of carbon for the arc has a value as given by Selwyn which differs from the value found for the spark. For the carbon groups at 1656 and 1560 values are obtained very close to the accepted ones. The tin wave-lengths are 1899.875, 1831.75, 1811.206, 1757.91, 1699.39. For the last two the error is about 0.03A.