The Magnetic Storm of May 14, 1878, Observed in North America

Abstract

THE extensive magnetic disturbance of May 14, 1878, of which accounts have been given in NATURE, vol. xviii. pp. 617, 641, 668, and which was observed in China, Australia, and England, was also making its record in North America at our magnetic observatory, established at Madison, Wisconsin, in the winter of 1876–77. This observatory is in latitude 43° 4′ 29″.5, and in longitude 5h. 57m. 36.5s. W. of Greenwich; in it are mounted a set of Brooke's magnetographs, and daily photographic traces of the changes in magnetic declination and in the horizontal and vertical forces have been produced since March, 1877, and are intended to be kept up for some years. The declination traces for several days preceding the 14th were normal, but about midnight, May 13–14, a series of disturbances commenced consisting in part of some large oscillations to the eastward and westward, and in part of a great number of small and rapid oscillations. The characteristic features of the trace may be given as follows:—