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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.

Lemström’s conclusions.

M. Lemström concluded that an electric discharge of an auroral nature, which could only be detected by means of the spectroscope, was taking place on the surface of the ground all around him, and that, from a distance, it would appear as a faint display of Aurora.

[It should, however, here be noted that the reflection of an Aurora from a white or bright surface would give, in a fainter degree, the spectrum of the Aurora itself; and, apart from the phenomena seen by the eye, the case fails to be conclusive that an Aurora on the surface of the ground was examined.]