4. Observations of Prof. ALEXANDER C. TWINING on the Aurora of Aug. 28th, 1859, made at West Point, New York.

While the evening twilight was yet so strong as to make the phenomenon scarcely discernible, a rosy hue was seen spreading over a space reaching from the northeastern horizon to the north star and thence to my zenith, of uniform breadth throughout, and bounded south by a line through Alpha Lyrae, passing vertically down to the east. The time was 7b 25m by the watchwhich however varied six minutes from true local time (too fast it is believed, making the local time 7h 19m). In about ten minutes the southern boundary moved to Alpha Aquilae, and the rosy light had extended itself visibly over to the west, and streamers were seen in the northeast. Very soon the northern sky became variegated nearly up to the zenith with advancing bands and flakes of yellowish and reddish cloud with streamers intermixed. At a quarter before eight o'clock, by estimation of the true local time, the streamers in the north were numerous; and by careful observation they were perceived universally to move towards the west.

At 8h 35m (by the watch) I looked again. A corona was then formed, and the auroral clouds and streamers were colored with tints of red and yellowish white. The most remarkable phenomenon was exhibited at the southern margin of the illumination. A yellowish cloud of extraordinary density and low altitude was seen advancing southward with an even and massive boundary which stretched entirely across the sky, in striking contrast with the clear blue beneath. It advanced beyond the bright star Antares, but soon receded and took a position which it retained ten or twelve minutes in a nearly level line exactly through that star, and a degree and a half, by estimation, below the star Epsilon Sagittarii. Its altitude therefore during that period-say from 8h 40m to 8h 50m (local time)-was about 111°, at the first named star, and about 11° at the last:-at the meridian it was, probably, 12°. This southern line gave an opportunity for comparative observations in different latitudes, which, if improved, will determine the height of that auroral cloud with an unparalled certainty and accuracy. There was also during this period another phenomenon equally remarkable and, if extensively observed in widely different latitudes, equally valuable. Ten or fifteen minutes before nine o'clock a bright spot formed at or near the meridian, and three or four degrees below the above named level margin. It soon became a long and narrow cloud-say 8° long and 21° broad at the middlebut pointed at its eastern and western extremities. It moved to the west in the clear sky, and parallel to the cloudy margin above it. In its course it passed centrally over the pair of

bright contiguous stars in the end of the Scorpion's tail,—showing an altitude, at the cloud's middle line, of 7°. In two minutes as I estimated from subsequent recollection-it moved about forty degrees. It then was hidden by the mountains in the vicinity. Soon after this disappearance it was observed that the entire expanse of cloud in the south from the zenith down was making a similar progress west,-at about the same rate, as nearly as could be estimated. At 8h 52m (local time) the original mass of vapor had moved nearly out of the southern field-leaving a far less dense and bright accumulation of cloudy strata over all that quarter.

At twenty minutes to a quarter before ten o'clock I observed again. The corona was then finely formed by streamers thickly and completely developed on every side. In about three minutes the display became suddenly very gorgeous, the red and white (yellowish-white) streamers and banks being very brilliant. So they continued for a quarter of an hour at least. In this period pulsations or auroral waves were seen propagating themselves rapidly upwards, and quite to the corona. That these did move upwards was determined by a close scrutiny. The dome was completed on every side. The southern streamers were particularly observed to originate beneath in a line or arch which I roughly, and without express verification, judged to be at about the altitude of the cloudy margin as observed at a little before nine o'clock. It may have been somewhat higher. At ten o'clock, or a little earlier, the phenomenon of the narrow cloud moving westward was strikingly repeated. The cloud however in this instance was longer and less definite in shape.

From ten o'clock to 12h 15m I did not observe. At this last mentioned time the auroral twilight shone brilliantly in the north, but my view in that quarter was obstructed.

I observed again from 2h 45m to 3h. The corona and dome were more regularly and completely formed than previously at ten o'clock, and more than I have seen them in either of the grand auroras of the last thirty years. The streamers were narrow, thick set, evenly distributed, and traceable to the corona. High in the north, observed against the constellation Cassiopeia, they moved across it from west to east, contrariwise to the motion in every instance I have before observed in any aurora. Yet my morning observations on this particular (and nearly or quite universal and yet generally unnoticed) phenomenon of transverse motion have not been so numerous as at evening.* At the spot

* My conjecture as to the ocension of this remarkable feature of auroral phenomena has heretofore been the following:-a streamer may be taken as the visible path of some portion of an electric current, normal, or nearly so, to the great thermal current of the earth. Such a normal current, in conformity with known laws, will experience a lateral movement under influence of the thermal current. It will also act upon the latter, thus affecting magnetic intensity at the earth's surface, and,

observed the motion was estimated as being fully 20° per minute. The ever varying wisps of cloud at the corona, and the southern streamers were also moving to the east. I left the display in full action without observing farther.

The repetition which took place Sept. 3d, although on a vastly diminished scale of grandeur, I observed about one hour,-say from 9h to 10h P. M. It was remarkable for the character of the auroral waves, which passed upward, illuminating successively different definite spaces in their path. The motion of these waves was far more moderate than I have ever before remarked. In this instance I could not estimate it to exceed forty-five degrees of arc in a second of time. The movement was everywhere distinctly upward; but the determination of arcual or angular motion in this phenomenon, is excessively difficult and in

exact.

5. Two letters from Prof. Daniel Kirkwood, Bloomington, Ind.

Gentlemen:-The most extraordinary display of the Aurora Borealis I have ever witnessed was seen from this place last night. It was observed immediately after the close of twilight, and, in the course of an hour, the whole northern horizon from east to west was illuminated. The phenomenon continued from twilight to twilight; the brilliancy being greater at 4 o'clock this morning than at any previous hour. It was the lightest moonless night our citizens have ever known. Tints of various colors were seen in different parts of the heavens; but what struck spectators generally with wonder was a thin, gauzy cloud of brilliant red, which appeared first in the east about 9 o'clock in the evening, and which seemed to move almost horizontally till it reached the northwest; at 9h 30m lying precisely over the stars Alioth, Mizar and Benetnash, where it took the form of streamers, converging towards a point somewhat south of the zenith. At the same time an arch of light appeared, having one extremity in the horizon beneath, or rather westward of, almost of necessity the declination and dip; which seem to be merely resultants of all the electro-dynamic actions upon the needle, subsisting at the time. Under the above hypothesis, therefore, every development of streamers must ordinarily concur with three other phenomena, viz., a lateral movement of the streamers, a change of the needle's direction, and a change of magnetic intensity. The hypothesis of a magnetic property in the auroral medium-whatever the latter be-seems wholly gratuitous. It is only requisite that the medium, or substance through or along which the current passes, shall be susceptible of illumination by such passage. Certain phenomena however indicate that the current transports the auroral vapor laterally with itself. The importance of this class of observations to questions relating to the cause of the aurora, as well as to the direction of currents, is obvious.

these red streamers, the other in the southeast; the zenith distance of its summit being about 40°, and its outer edge just reaching Arcturus.

Subsequently a splendid corona was formed, towards which the streamers moved in beautiful undulations. The most remarkable feature in the phenomenon, however, was its extent; not only the entire northern part of the visible hemisphere was illuminated, but the greater portion also of the southern.

I have just learned that during the night some lines of the magnetic telegraph were so much disturbed as to stop communication between different points.

[Second letter.]

Bloomington, Indiana, Sept. 9th, 1859.

TO THE EDITORS, &c.

Gentlemen:-Since the date of my hasty note of the 29th ult., we have had several more displays of the Aurora. Not having witnessed them myself, however, I have collected from others the following facts in regard to them: the first-a magnificent one was seen by many of our citizens on the night of September 1st. It was noticed in the north about 11 o'clock, and gradually increased in brilliancy and extent until the whole visible heavens were illuminated; the light at times being such that ordinary print could be read without much difficulty. At I o'clock in the morning the portion of the heavens in which the light was most intense was almost exactly southeast, about midway between the zenith and horizon. The Stark County (Ill.) News thus describes the phenomenon :

"On yesterday morning, (Sept. 1st) between one and two o'clock, the whole heavens were aglow with deep red light, which presented every variety of beautiful aspect imaginable. When we first looked out, it looked as if two brilliant suns had just set, one in the east and one in the west, and the sky, at either point was painted in broad streams of crimson and gold. This lasted but a moment, then a deep glow overspread the whole sky, brighter at some points than others, but all red. The light was so strong at times, that we could see to read fine print with ease, and gave to buildings and other objects, a dim glow, like fire-light. An arc of some 20° was formed over the southern horizon, the inside of which presented a silvery appearance like the edge of a cloud brightened by the moon, and from this, broad streams of a lilac color would flash up toward the zenith and abruptly end."

The displays on the nights of the 1st and 2nd, are described by the Indianapolis Journal of the 3rd inst., as follows:

"Another Aurora.-Yesterday morning (Sept. 1) from midnight till day another Aurora, more brilliant than the first, in this locality at least,

was witnessed by those who had the good luck to be up at that time. At half past 11 o'clock it was quite brilliant, as a low arch of pure white light in the north, with but few radiations of colored light, and none that rose very high. It was very luminous, we could see as plainly as by moonlight, when the moon is quarter full, though the light was a paler and more ghastly kind, more like faded daylight than moonlight. Later in the night it grew much brighter still, and extended over the whole visible heavens. A beautiful column of red rays rose in the northeast, and another rose in the northwest, and met in the zenith, and from this point of junction a flood of red light poured out over the sky running down to the horizon on all sides, south as well as north, and the whole earth colored under its beautiful but ghastly crimson. Many who saw it say it was far more brilliant than the one of Sunday night, and it certainly was much more luminous, though less marked by the darting rays and wonderful pulsations that made the first so splendid. It was seen at Cincinnati, and all over the Union, we suppose, as the first one was. Such frequency and splendor of Auroras at this season we never saw or heard of before.

"Still another.-Another very beautiful Aurora Borealis was seen last night (Sept. 2) about half past eight o'clock. At that time it was confined to the north entirely. The rays shot up in very distinct cones or peaks of light, and beautifully variegated in color.

On Monday the 5th, about 2 o'clock in the morning, the phenomenon was witnessed for the fourth time within a week. Several beautiful streamers shot up from the northwest towards the zenith. The light, however, was of short duration.

It may be proper to remark that last evening, the 8th, about 9 o'clock, notwithstanding the bright moonlight, indications of the Aurora were again discoverable.

6. On the Meteorological and Magnetic Phenomena accompanying the Aurora Borealis of Aug. 28th, 1859, as observed at Springhill (near Mobile), Alabama; by Prof. A. CORNETTE, S. J.

I have thought that the meteoric conditions which preceded, accompanied and followed the Aurora Borealis of August 28th would be read with interest by all who witnessed that phenomenon on this memorable occasion. I copy from my daily journal without translating the French metrical numbers which I have for many years employed.

I add some hourly observations upon the perturbations of the magnetic current after the phenomenon, as well also as some observations on the subject at large.*

* In conformity with our design to give at present only facts, we reserve Father Cornette's ingenious speculations to another occasion.