Wave-Length Standards in the Spectra of Aluminum. Silicon and Bismuth in the Schumann Region

The second order spectra of these elements have been photographed along with first order iron lines with a two meter vacuum grating. Between 1900 and 1500A values are found for the aluminum lines which check very closely the work of Bowen and Ingram. The silicon wave-lengths are 1816.922, 1808.01, 1533.42 and 1526.71. For bismuth the values are 1902.33, 1823.71, 1791.82, 1787.39 and 1777.01. These values are believed to be accurate to within about 0.02A.