Page:Popular Science Monthly Volume 59.djvu/38

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28
THE POPULAR SCIENCE MONTHLY.

and character, but I made a series of eight sketches at intervals of about twenty minutes apart, which illustrate the most striking changes. The second form was a homogeneous arc with a fragment of a second arc under it. This hung for some time, with a steady nebulous glow between it and the one previous, as ^yell as between the intervening periods of all. The following typical forms then were rapid and almost imperceptible gradations. The third sketch represents the same position on the heavens; but under it are portions of two other arcs and a suggestion of a luminous horizontal line. At times a wave of rays, converging to the pole of the circle described, ran over the main arc. In the fourth sketch there are two arcs and a portion of a third which were seen persistently in all the exhibits to be present. In the fifth there is a second arc crossing the first. This was suggested by the

 

PSM V59 D038 Early display of the aurora australis.png

March 26. Early Display. This was Followed by Darting Rays and Wavy Ribbons which Ended in a Brilliant Arc with Moving Ray's Drawn Over it Converging to a Common Center, as Shown Below.

 

PSM V59 D038 Later display of the aurora australis.png

March 26. Later.

 

third, and it reappeared in the seventh. The sixth form was an arc with three ribbons of luminous beams waving from side to side. The exhibit ended with a plain arc aglow with a steady light.

For a week following we had faint auroral displays every night, but we seldom saw a brilliant or extensive exhibit. The usual form it took at this time was that of a fragment of one or several arches. On the night of the 26th we saw the usual auroral patches in the southeast which we had seen so often before. These disappeared entirely at ten o'clock, but reappeared shortly after in a manner and vividness worthy of note. There was a steady luminous bow somewhat brighter than the Magellanic clouds, and over this there were bunches of brighter rays with a rapid motion from east to west. These rays centered to a point below the horizon. Under this main arc there was from time to time a suggestion of a second and also a continuation of the same