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.