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Lu, the telegraph "fires" from the 1859 solar flare make sense when you consider the nature of some telegraph systems at that time. There were still several different designs of telegraph lines particularly the devices used for sending and receiving messages. The standard telegraph key eventually won out as the best solution but that was still a few years in the future in 1859. In England, for example, messages were received by watching twitching needles in gauges. I remember reading somewhere that operators had a particular code that they could send at just the right rate to make the needles "laugh" --an early version of typing "LOL" (there were other such shorthands for operator jokes and comments invented in different countries). Another system used a primitive form of thermal printing. A doped paper strip would run through the receiving equipment and the electrical sparks generated as a message was received would make visible dots and dashes on the paper. It's this sort of system that apparently led to fires. The solar storms impacted the earth's magnetic field causing fairly abrupt changes in direction of the field lines over hundreds of miles. And changing magnetic fields do their Faraday duty inducing currents in those long electrical lines of early telegraph systems. That steady current, above normal levels, then lit the paper on fire.

I looked into this a few years back because an online acquaintance, also someone with an extensive background in modern electrical engineering, expressed the same doubts you had about the veracity of these stories. When you go back to the original sources, it all makes fairly good sense. These were primitive electrical systems, and they were prone to just this sort of long-distance emf from solar storms.

-FER

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