Twenty lines in the visible spectrum, $\lambda 7688$ in the infrared, and the two resonance lines $\lambda 3383$ and $\lambda 3281$ were studied by means of a hollow cathode source and Fabry-Perot interferometers. All lines in the visible were found to be simple in agreement with the findings of other investigators. $\lambda 7688$ was found to be a very broad line and lines $\lambda 3383$ and $\lambda 3281$ were each found to be double with the weaker component on the longer wavelength side. Photographic plates measured gave an average of 0.055 ${\mathrm{cm}}^{-1\mathrm{}}$ for the separation in $\lambda 3383$ and 0.056 ${\mathrm{cm}}^{-1\mathrm{}}$ in $\lambda 3281$. It is concluded that the doubling of these lines is due to a splitting of the $5S$ level because of nuclear spin which is probably 3/2.

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