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Renewed interest was aroused by the remarkable earth‐current disturbances of May 14 to May 20, 1921, and, as will be recalled, there were also at the time brilliant displays of polar lights, severe magnetic storms, and manifestations of pronounced solar activity. These disturbances and accompanying phenomena occurred over the entire Earth. Northern lights were observed in lower northerly latitudes than usual, and southern lights were seen as far north in the Southern Hemisphere as Apia, Samoa—a very unusual occurrence. In certain respects the disturbances, during the period mentioned, were similar to those which occurred August 29 to September 4, 1859.
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Louis A. Bauer (1922) studied this question.
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