Wave-Lengths of the TungstenKSeries Spectrum with the Double Spectrometer

With a Société Genovoise double spectrometer and the method devised by Compton the $K$ series wave-lengths of tungsten were determined from the diffraction angles in the first order from calcite. The results, corrected for slit heights and reduced to 18°C are: The wave-lengths are calculated assuming a grating constant $d=3.02904\mathrm{}\mathrm{A}$ at 18°C. The separation of ${\alpha }_1$, ${\alpha }_2$ agrees exactly with the energy difference $L_{\mathrm{II}}-L_{\mathrm{III}}$. The ${\beta }_1$, ${\beta }_3$ lines are easily resolved in the first order and give a separation of 0.78 x. u. agreeing closely with the energy difference $M_{\mathrm{II}}-M_{\mathrm{III}}$. Some remarks are made on the measurement of the natural widths of W $K$ series lines.