Page:Popular Science Monthly Volume 23.djvu/178

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principal features of the spot are here represented, but the reader will be able to get a better general idea of the changes that occurred from such a picture than he could from one filled with minor details. The central and lower portions of the figure are especially worthy of attention because of the indications they give of an eddying motion corresponding with what should always be seen in a sun-spot according to Faye's cyclonic theory, but which, in fact, is rarely visible. It was also in these parts of the spot that the principal changes occurred, as will be seen by reference to the figures. It is very interesting to note that in Carrington's drawings of the remarkable sun-spot which accompanied the great magnetic storm of September, 1859—a disturbance whose effects strikingly resembled those produced by the storm of last November—similar indications of a whirling motion can be detected. Another exceedingly interesting fact is that in England, on the 16th of November last, luminous points were seen rapidly crossing the great spot. This forcibly recalls the similar phenomenon of flying points of light, seen by Carrington and Hodgson, darting across the spot of 1859, and which seemed to be a signal for the outbreak of the magnetic storm that followed.

PSM V23 D178 November 18 sunspot with major magnetic storm.jpg
Fig. 2.

In Fig. 2, which represents the spot as it appeared on the 18th, the day after the great magnetic storm, evidences of cyclonic motion are still, perhaps, visible, though they are rather suggested by a comparison of the appearance of the spot with that shown in the previous figure than by any clear indications in the figure itself unconnected with the other one. The roundish, nuclear mass near the center suggests by its form a whirlpool-like motion, but it is difficult on that hypothesis to account for the long, straight channel connecting it with the oblong figure on the right. The peculiar crooked figure seen in the lower part of the first picture has, it will be perceived, apparently broken up into several fragments, but this by itself is not inconsistent with the theory of an eddying motion.

Fig. 3 represents the appearance of the spot on November 19th, auroras and magnetic disturbances having in the mean time continued. Still further changes, it will be seen, have taken place, and the lower portion of the spot shows a tendency to separate from the larger mass above—a phenomenon that is of not unfrequent occurrence.