from the magup

magnetic meridian; in another, the beam shot netic north to the zenith; and in both these cases, the needle moved towards the west.'

"The needle was most disturbed on February 13 [1821], p. m. at a time when the Aurora was distinctly seen passing between a stratum of clouds and the earth, or at least illuminating the face of the clouds, opposed to the observer. This and several other appearances, recorded in the accompanying notes, induced me to infer that the distance of the Aurora from the earth varied on different nights, and produced a proportionate effect on the needle. When the light shone through a dense hazy atmosphere, when there was a halo round the moon, or when a small snow was falling, the disturbance was generally considerable; and on certain hazy cloudy nights, the needle frequently deviated in a considerable degree, although the Aurora was not visible at the time. Our observations do not enable us to decide whether this ought to be attributed to an Aurora concealed by a cloud or haze, or entirely to the state of the atmosphere. Similar deviations have been observed in the day-time, both in a clear and cloudy state of the sky, but more frequently in the latter case. Upon one occasion, the Aurora was seen immediately after sunset, while bright day-light was remaining.'

"A circumstance to which I attach some importance must not be omitted. Clouds have been sometimes observed during the day to assume the forms of the Aurora, and I am inclined to connect with the appearance of these clouds the deviations of the needle, which was occasionally remarked at such times."

"An Aurora sometimes approached the zenith, without producing any change in the position of the needle, as was more generally the case, while at other times a considerable alteration took place, although the beams or arches did not come near the zenith. The Aurora was frequently seen without producing any perceptible effect on the needle. At such times its appearance was that of an arch or an horizontal stream of dense yellowish light, with little or no internal motion."

"The disturbance in the needle was not always proportionate to the agitation of the Aurora, but it was always greater when the quick motion and vivid light were observed to take place in a hazy atmosphere."

"In a few instances, the motion of the needle was observed to commence at the instant a beam darted upwards from the horizon. And its former position was more quickly or slowly regained according to circumstances. If an arch was formed immediately afterwards, having its extremities placed on opposite sides of the magnetic north and south to the former one, the return of the needle was more speedy, and it generally went beyond the point from whence it first started."

"When the disturbance of the needle was considerable, it

seldom regained its usual position before three or four p. m. on the following day."

"On February 13, at 11h 50m p. m., the needle had a quick vibratory motion between 343° 50′ and 344° 40'. This is the only occasion on which a vibratory motion was observed.”

The disturbances produced by the Aurora were so great, that no accurate deductions could be made respecting the diurnal variation."

"I have not heard the noise ascribed to the Aurora, but the uniform testimony of the natives and of the residents in this country, induces me to believe that it is occasionally audible. The circumstance, however, must be of rare occurrence, as is evidenced by our having witnessed the Aurora upwards of two hundred times without being able to attest the fact. I was almost inclined, last year, to suppose that unusual agitations of the Aurora were followed by storms of wind; but the more extended opportunities I enjoyed of observing it in 1821, at Fort Entreprise, have convinced me that no such inference ought to have been drawn."

"The Pith Ball Electrometer, which was placed in an elevated situation in the air, never indicated an atmosphere charged with electricity." P. 551-553.

The succeeding remarks and experiments on this curious subject were made at Fort Entreprise, by the ill-fated Lieut. Hood, and are extracted from his Journal.

"On the 27th of April, 1821, at 10h 30m p. m., a single column of Aurora rose in the north, and traversed the zenith towards the south; another column appearing, NE by E and taking a parallel direction. The frost was slightly agitated, and the beams momentarily visible. It passed to the western horizon in ten minutes, and was followed by the other, which became brighter as it approached the zenith. I am now convinced they were borne away by the wind, because the columns preserved exactly their distance from each other during their evolution; and some detached wreaths, projected from them, retained the same relative situations of all their parts; which never happens when the Aurora is carried through the air by its own direct motion. The wind was E by N, a strong gale, and the temperature of the air 9°."

"It must be admitted that the influence of the wind upon the Aurora was never suspected until the 27th of April. However, there are several partículars connected with the subject, which may have prevented such an influence from manifesting itself on former occasions. 1st. When the coruscations were rapid and brilliant, they forced themselves against the wind, or in the contrary direction, without any perceptible difference of speed; from which circumstance, I was led to suppose that they were not in any degree affected by the wind, and did not afterwards pay sufficient attention to discover my error,

2d. The prevailing winds were from the eastward and westward; and the arches usually extending from NW to SE; the influence of the wind might have been mistaken for their lateral motion. 3d. The northerly winds, acting from the same quarter as the direct motion, were confounded with it. Lastly, the southerly winds, which were not common, always filled the atmosphere with clouds, so that the Aurora was not visible. Perhaps, after all, the Aurora of the 27th of April was nearer to the earth than any other which we saw."

"On the 11th of March, at 10 p.m., a body of Aurora rose NNW, and after a mass of it had passed to E by S the remainder broke away, in portions consisting each of several beams, which crossed about 40° of the sky with great rapidity. We repeatedly heard a hissing noise, like that of a musketbullet passing through the air, and which seemed to proceed from the Aurora; but Mr. Wentzel assures us, that this noise was occasioned by severe cold, succeeding mild weather, and acting upon the surface of the snow, previously melted in the sun's rays. The temperature of the air was then 35°, and on the two preceding days, it had been above zero. The next morning it was 42°, and we frequently heard a similar noise. Mr. Hearne's description of the noise of the Aurora agrees exactly with Mr. Wentzel's, and with that of every other person who has heard it. It would be an absurd degree of scepticism to doubt the fact any longer; for our observations have rather increased than diminished the probability of it." P. 584, 585.

"The common cork-ball electrometer not having on any occasion given signs of a charge, I tried the following experiment, in order to attain further evidence on the subject. A brass needle was attached to a compass card, and balanced on a copper pivot in a wooden box. It was about four inches in radius, and a copper arch of 60° to that radius, was fixed at one end of the box, which was closed by a wooden slide, and paper pasted over every crevice to exclude the air. To give it the same advantages for conducting electricity as the compass boxes (which are made of brass), I introduced an iron. wire, eight inches in length, perpendicularly through the lid, in such a manner, that its lower extremity was in a horizontal plane with the needle; and a pane of glass at that end of the lid, enabled me to see into the interior of the box. Having previously ascertained that it contained no magnetism, the instrument was placed, on the 2d of May [1821], on a covered shelf, at the outside of the house, in a position nearly east and west; the brass needle being 25′ from the conductor, and a small glass bubble adjusted on the box, in order to prevent its otherwise unperceived movement. At 12h At 12 p. m. I examined the needle, and found its position unaltered. No Aurora was then visible, but one was afterwards seen by Mr. Franklin;

and at 8h a. m., May 3d, the needle and conductor were in contact. I moved the needle 40' from the conductor, and it was similarly affected at some period on the nights of May 3d, 5th, 6th, 9th, 10th, and 11th. The thermometer, during this period, ranged in the day between +26° and + 56°; and in the night, between +10° and +33°. I did not see the Aurora, except on the nights specified above; and did not perceive any alteration in the needle till the succeeding mornings."

"The night of the 12th furnished a more satisfactory proof of the agency of the Aurora. At 10h p.m. the needle was not affected, and no Aurora was visible. At 0h 30′ a. m. May the 13th, several arches appeared across the sky from NW to SE, and the needle was attracted to the conductor from the distance of 1°. The temperature of the air was + 12°. I now determined to convert the instrument into a kind of electrometer, by insulating the needle and conductor. The pivot which supported the former was fixed upon sealing wax, and the point of the latter, which passed through the lid, was covered with the same substance.'

Paper was pasted on the box as before, and it was re-placed at 2 p.m. on the 14th, the temperature of the air being 54°. A heavy gale of wind from NNW, with snow, immediately followed, and the temperature of the air, at midnight, was reduced to 19°. At 9h a. m. May 15th, the needle was removed 30° from the conductor, and both were still charged, so that I could not bring them together till the conductor was accidentally touched. I believe this change to have been received from an Aurora; because the same weather, preceding and following it, did not affect the needle in the day, when the increased warmth of the air was more favourable to the production of electricity in other quarters, and also to its passage. On the 24th of May, between 10 and 12h p.m. the needle was attracted to the conductor, and repelled 25°.* The next morning, Mr. Franklin found the needle of the transit instrument (which was then in the meridian) affected 20'. The brightness of the twilight prevented us from seeing the Aurora, and I therefore discontinued my observations."

"That electricity was the cause of the motions which I have described does not admit of a doubt. But whether the electricity was received from, or summoned into action by, the Aurora, my readers will determine for themselves, being in possession of the facts upon which I have myself founded my opinion." P. 586, 587.

Dr. Richardson is of opinion, that, independently of all theory, his notes "will at least serve to prove that the Aurora is occasionally seated in a region of the air, below a species of cloud which is known to possess no great altitude. I allude to

"The thermometer was then 20°, and at 3h p. m. it had been 58°."

that modification of cirro-stratus, which, descending low in the atmosphere, produces a hazy continuity of cloud over-head, or a fog bank in the horizon. Indeed, I am inclined to infer, that the Aurora Borealis is constantly accompanied by, or immediately precedes, the formation of one or other of the various forms of cirro-stratus. On the 13th of November, and 18th of December [1820], its connexion with a cloud intermediate between cirrus and cirro-stratus is mentioned; but the most vivid coruscations of the Aurora were observed when there were only a few attenuated shoots of cirro-stratus floating in the air, or when that cloud was so rare that its existence was only known by the production of a halo round the moon. The bright moonlight of December was peculiarly favourable for observations of this kind. Had the nights been dark, many of the attenuated streaks of cloud hereafter mentioned would have een totally invisible." P. 597.

"I think I have on some occasions discerned," Dr. Richardson continues, "a polarity in the masses of cloud belonging to a certain kind of cirro-stratus, which approaches to cirrus, by which their long diameters, having all the same direction, were made to cross the magnetic meridian nearly at right angles. The apparent convergence of such masses of cloud towards opposite points of the horizon, which has been frequently noticed by meteorologists, is of course an optical deception, produced when they lie in a plane parallel to that on which the observer stands. These circumstances are here noticed, because if it should be hereafter proved that the Aurora depends upon the existence of certain clouds, its apparent polarity may, perhaps, with more propriety, be ascribed to the clouds themselves which emit the light; or, in other words, the clouds may assume their peculiar arrangement through the operation of one cause (magnetism for instance), while the emission of light may be produced by another, a change in their internal constitution perhaps, connected with a motion of the electrical fluid. .... Generally speaking, the Aurora appeared in small detached masses for some time before it assumed that convergency towards the opposite parts of the horizon, which produced the arched form. An observation that I would .connect with the previous remarks, by saying that it was necessary for the electric fluid (or the Aurora, if they are the same) to operate for some time before the polarity of the thin clouds, in which it has its seat, is produced.'

"An electrometer, constructed upon Saussure's plan, placed in an elevated situation out of doors, exhibited no signs of a charge from the atmosphere at any time during the winter. The electricity of our bodies, however, at times was so great, that the pith balls instantly separated to their full extent upon approaching the hand to the instrument; and our skins were in the middle of winter so dry, that rubbing the hands together