Mixed colours. Colours change. Tongues of white flame formed.
The colour of the light was chiefly red; but every tint had its turn, and sometimes two or three were mingled; blue and yellow streamers shot across the terrible glare, or, starting side by side from the wide expanse of the radiant arch, melted into each other, and flung a strange shade of emerald over the illuminated landscape. Again this green subdues and overcomes the red; then azure and orange blend in rapid flight, subtle rays of violet pierce through a broad flash of yellow, and the combined streams issue in innumerable tongues of white flame, which mount towards the zenith.
The illustration which accompanies this description in the work is reproduced on Plate II., and forcibly reminds one of the “curtains” of the Aurora described in the preceding Chapter by Mons. Lottin.
Plate II.
Prof. Lemström’s Aurora of 1st September, 1868.
Prof. Lemström’s Aurora, 1st September, 1868.
In the first Swedish Expedition, 1868, some remarkable observations were made on the appearance of luminous beams around the tops of mountains, which M. Lemström showed by the spectroscope to be of the same nature as Auroræ.
Aurora from earth’s surface. Yellow-green line seen.
On the 1st September, 1868, on the Isle of Amsterdam in the Bay of Sweerenberg, there was a light fall of snow, and the snowflakes were observed falling obliquely. All at once there appeared a luminous phenomenon which, starting from the earth’s surface, shot up vertically, cutting the direction of the falling snowflakes, and this appearance lasted for some seconds. On examination with a spectroscope the yellow-green line was found by Lemström (but of feeble intensity) when the slit of the instrument was directed towards a roof or other object covered with snow, and even in the snow all round the observer.