Abstract
THE author gives chiefly the results of his spectrum observations, and simultaneous spot observations, recorded in the Transactions of the Berlin Academy of Sciences for November 1871, and May 1872. To the two earlier instances of striking changes observed in the protuberances, there is added an interesting observation of August 8, 1872. It was estimated that the prolongation of the upper part of the protuberance had a velocity of forty-two kilometres per second, parallel to the sun's surface. In the case of many protuberances, it will be readily allowed that they are not only subject to cyclones, but also owe their origin to them. Protuberances of similar form, observed on several successive days, in the same heliographic latitude, Spörer has accounted for, by the supposition of volcanic eruptions, owing to the smaller rate of linear rotation of the deeper strata; if, however, we regard these protuberances as the results of cyclones, the explanation of the changes of position would rest upon the impelling power of the storms, and their tendency to create new forms; and the velocity of the advancing cyclone would, in several instances, average 1.4 kilometre.
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Spörer's Observations on the Sun * . Nature 8, 391 (1873). https://doi.org/10.1038/008391a0
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DOI: https://doi.org/10.1038/008391a0