The 14 –15 May 1921 aurora was observed from Europe, across North America and the Caribbean, and in the Pacifc as far west as Australia. From observations in England, Chree (1921) judged the most disturbed period of the magnetic storm to be from 0000 to 0800 GMT (UT) on 15 May, with the subinterval from 0300 to 0730 UT being particularly active. This subinterval corresponds to local times from 2200 (14 May) to 0230 (15 May) on the east coast of the United States, 1900 –2330 (14 May) on the west coast, and 1300 –1730 (15 May) in Melbourne, Australia.
2.3. Effects on telegraph, cable and wireless: Effects of the storm on communications were widespread and severe. In New Zealand (Gibbs, 1921), for example, signals at all radio stations were very erratic, telegraph lines suffered from violent fluctuations of current, and unusual interference was experienced at certain telephone exchanges.
Overall the disturbances were of greater magnitude and more far-reaching than had previously been observed in New Zealand. In the United States telegraph service was affected to an unprecedented extent, such that on the 14th service virtually ended near midnight on lines from the Atlantic Coast to the Mississippi (New York Times, 15 May 1921). In one instance it took an operator nearly an hour and a half to transmit 150 words from Bethlehem, Pennsylvania to the New York Times. Wireless signals from Berlin, Germany and Bordeaux, France, however, were strengthened. The storm was reported to have “blown out fuses, injured electrical apparatus and done other things which had never been caused by any ground and ocean currents known in the past”. It was anticipated that ships would have to drag up submarine cables to repair the damage (New York Times, 17 May 1921). The storm was reported to have burned out a telephone station in Sweden, and probably to have contributed to a fire in a New York signal tower. French telegraph lines were also affected, and “seemed possessed by evil spirits”. The Central New England Railroad station in Brewster, NY was destroyed by a fire which originated in the telegraph. The telegraph operator said that “he was driven away from his instrument by a Hare of Fame which enveloped the switchboard and ignited the building”. In the western United States telegraph communication was disrupted in Denver, Colorado; Salt Lake City, Utah; San Francisco,
California; Seattle and Spokane, Washington; Winnemucca, Nevada; and Helena, Montana. Cable and telegraph lines to Alaska were completely out of commission for a time (Lyman, 1921).