"The cauld blue North was flashing forth Her lights wi' hissing eerie din."
It finds confirmation also in the fact, generally admitted by the inhabitants of the northern regions, that, when the auroras appear low, a crackling is heard similar to that of the electric spark. The Greenlanders think that the souls of the dead are then striking against each other in the air. M. Ramm, Inspector of Forests in Norway, wrote to M. Hansteen, in 1825, that he had heard the noise, which always coincided with the appearance of the luminous jets, when, being only ten years old, he was crossing a meadow covered with snow and hoar-frost, near which no forests were in existence. Dr. Gisler, who for a long time dwelt in the North of Sweden, remarks that the matter of the aurorae boreales sometimes descends so low that it touches the ground; at the summit of high mountains it produces upon the faces of travellers an effect analogous to that of the wind. Dr. Gisler adds, that he has frequently heard the noise of the aurora, and that it resembles that of a strong wind, or the hissing that certain chemical substances produce in the act of decomposition.
M. Necker, who has described a great number of aurorae which he observed at the end of 1839 and at the commencement of 1840, in the Isle of Skye, never himself heard the noise in question; but he remarks that this noise had been very frequently heard by persons charged with meteorological observations at the light-house of Swenburgh Head, at the southern extremity of Shetland. M. Necker is not the only observer who has not heard the noise; neither have MM. Lottier and Bravais, who have observed so great a number of aurorae, ever heard it; and a great many others are in this case. This may be due to the fact that it is necessary to be very near to the aurora in order to hear the crepitation in question, and also to the fact that it is possible that it does not always take place, at least in a manner sufficiently powerful to be heard.
We have just been pointing out, as concomitant effects of the aurora borealis, a noise of crepitation analogous to that of distant discharges, and a sulphurous odor similar to that which accompanies the fall of lightning. M. Matteucci also observed at Pisa, during the appearance of a brilliant aurora borealis, decided signs of positive electricity in the air; but of all phenomena, those which invariably take place at the same time as the appearance of the aurora borealis are the magnetic effects. Magnetized needles suffer disturbances in their normal direction which cause them to deviate generally to the west first, afterwards to the east. These disturbances vary in intensify, but they never fail to take place, and are manifested even in places in which the aurora borealis is not visible. This coincidence, proved by M. Arago without any exception, during several years of observation, is such that the learned Frenchman was able, without ever having been mistaken, to detect from the bottom of the cellars of the observatory of Paris the appearance of an aurora borealis. M. Matteucci had the opportunity of observing this magnetic influence under a new and remarkable form. He saw, during the appearance of the aurora borealis of November 17, 1848, the soft iron armatures employed in the electric telegraph between Florence and Pisa remain attached to their electro-magnets, as if the latter were powerfully magnetized, without, however, the apparatus being in action, and without the currents in the battery being set in action. This singular effect ceases with the aurora, and the telegraph, as well as the batteries, could operate anew, without having suffered any alteration. Mr. Highton also observed in England a very decided action of the aurora borealis, November 17, 1848. The magnetized needle was always driven toward the same side, even with much force. But it is in our own country that the action of the aurora upon the telegraph-wires has been the most remarkable.