The super storms of August/September 1859 and their effects on the telegraph system

The space weather event of August/September 1859 is now famous because of the observation by Carrington and Hodgson of a solar flare. However, at the time, the associated magnetic disturbances produced widespread auroral displays and disruption to telegraph transmissions which attracted much public attention and were widely reported in the newspapers and scientific articles. In this paper, I review all the available literature to assess the characteristics of the magnetic disturbances and the locations and times of the telegraph effects. This information is used to construct a timeline for the whole of the disturbed interval comprising the magnetic storms of August 28/29 and September 2/3. The first magnetic disturbance started in the evening of August 28 and telegraph operations were disrupted in North America and Europe through till the next morning. The second disturbance started with a sudden commencement at 04.40 UT on September 2 and a major disturbance followed immediately. Between 06.00 and 06.30 UT reports of a negative H variation of similar to 3000 nT at Rome and a large swing in Z at Greenwich indicate the expansion of the auroral oval to mid latitudes. This coincides with the time of the large disturbance at Bombay but there is no evidence that the auroral currents contributed to the Bombay disturbance. This initial disturbance subsided but magnetic activity increased again in the latter half of September 2 with lesser activity occurring on subsequent days. Telegraph operation in Europe was severely affected by the initial magnetic disturbance. In North America, 5 or 6 hours behind in local time, this initial disturbance occurred during local night time and the telegraph was not operating. Instead, the North American telegraph were affected by the second phase of the disturbance. During this time a notable event occurred when the operators of the telegraph in the Boston area disconnected their batteries and were able to send messages using only the "celestial power" induced in the telegraph lines by the magnetic disturbances. (c) 2006 COSPAR. Published by Elsevier Ltd. All rights reserved.