Certain minor mechanical errors occasioned by small flexures in some components of our 2-meter curved crystal $\gamma$-ray spectrometer were discovered recently through comparison of wavelength measurements in different orders of reflection. These errors and the means adopted for their correction have been described in published papers and a program of redeterminations of nuclear $\gamma$ and x-ray wavelengths is underway. In this program, a by-product of the study of the radioisotope ${\mathrm{Ta}}^{182}$ has led to measurements of the tungsten $K$-series x-ray lines, since tungsten is the daughter product of $\beta$ decay of ${\mathrm{Ta}}^{182}$. In this way we have obtained the following results: $\mathrm{W}-K{\alpha }_2=213.387\mathrm{}\pm 0.010$; $\mathrm{W}-K{\alpha }_1=208.575\mathrm{}\pm 0.008$; $\mathrm{W}-K{\beta }_3=184.785\mathrm{}\pm 0.027$; $\mathrm{W}-K{\beta }_1=183.997\mathrm{}\pm 0.019$ all expressed in x.u. (Siegbahn). The agreement with other measurements, particularly those given in E. Ingelstam's dissertation (1937), is now well within the estimated standard deviation of our measurements, and to avoid further confusion (because our earlier values disagreed slightly from Ingelstam's) we wish to announce that our earlier results [published in Phys. Rev. 75, 505 (1949)] are herewith superseded by these present ones.

• Received 17 May 1954

DOI:https://doi.org/10.1103/PhysRev.95.1203