I had added (at p. 140 of my paper on “Gaseous Spectra”) to the “small dispersion” account therein given of the above mentioned spectrum of luminous oxygen gas,—that two, if not four, of its very few and scanty lines appeared, when viewed with much higher dispersion, to be double; but that I hoped to give a more exact account of them, after completing some arrangements then in progress for increasing both the dispersion and magnifying power of my spectroscope.