As a result of a new mathematical analysis of the action of the double crystal spectrometer, a method of using the instrument has been found which makes it possible to determine the spectral energy distribution of an x-ray line and to calibrate the instrument without any previous knowledge of the diffraction patterns of the crystals.

• Received 28 May 1934

DOI:https://doi.org/10.1103/PhysRev.46.343