After the development of the telegraph, it was quickly discovered that the long lines used were often affected by mysterious induced electrical currents. And contrary to some of the speculation in this article, the effects actually weren't related to the weather, but instead were caused by radiation produced by solar flares.
New York Times, January 12, 1873, page 3:


Manifestations  of  the  Phenomenon  in  Western  States  Last  Week.
From the Chicago Tribune. Jan. 9.

    The storm which has just come over us from the North-west is a doubly remarkable one. Aside from its intolerable severity, it was accompanied by an electric storm, which is, in itself, a phenomenon. For two days past, the electric wave has swept over Iowa, Minnesota, Wisconsin, and Northern Illinois, rendering many of the telegraph wires entirely useless. This phenomenon is peculiar to the Winter season. The electricity pervading the atmosphere is not manifested in thunder and lightning as in Summer, but is frequently attended by brilliant auroral displays. These electric storms are most powerful when accompanied by high winds and falling snow. The fact that lines running east and west, or north and south, are alike affected, renders it extremely difficult to trace the origin or direction of the electric wave. Though not particularly unusual, it is still a phenomenon long familiar to telegraphers and electricians, yet little understood. Doubtless the United States Signal Service, with its abundant facilities for the collection of information, and the ability and opportunities to carefully and scientifically analyze them, will be able to deduce therefrom new and valuable electric laws intimately relating to the remarkable rain and snow-storms that occasionally deluge the country.
    The electric waves--so troublesome to the telegrapher--are variable in length, and vary from a second to one minute in duration. At times they act in conjunction with the battery current upon the wire, their united force grinding through the instruments with astonishing power, burning off the insulated covering from office wires, and melting the corners of brass machinery. All the marvellous power of lightning is displayed, though with less tension. No electricity is discernible upon the wires, and only at points where there are slight breaks is the flash visible. Extreme force is rarely exhibited. The storm generally expends itself in waves of moderate length, which rapidly follow each other, rendering the adjustment of instruments difficult, and the transmission or reception of messages impossible. An interesting feature is developed sometimes, when the atmospheric current runs in opposition to the battery power, and they neutralize each other, rendering the wires lifeless for the nonce, and indicating quite clearly that both are of equal strength. Were it not so, the stronger would neutralize the weaker, and still have power left for manifestation on the line. These considerations have led to a discovery that is grandly sublime. When the electric wave is of considerable duration and power, the operators have been known to let go their batteries, detach the wires, carry them to the ground, and, by means of the electric throbs, messages have been transmitted entirely independent of the ordinary auxiliaries. Many such instances are on record among telegraphers, but the experiments are necessarily brief, and, in practical results, unsatisfactory. In large telegraph-offices, where numerous wires centre to a common switch-board, the brass straps and faces are often illuminated by a constant succession of flashes interchanged between the several lines, which are harmless unless touched, and are beautifully attractive, especially at night.
    Yesterday afternoon this wonderful achievement was exemplified in the general office of the Chicago and North-western Railway. The chief operator took out both keys and left the wire to Clinton, Iowa, open at both ends. So fully surcharged with electricity was the atmosphere, that the wire could be easily worked without the use of the battery; indeed the force was greater with the key open than with the aid of the battery.
    The electric storm of Tuesday and Wednesday has been of unusual duration. It displayed the greatest severity in Iowa and out on the Western plains, placing an embargo upon telegraph communications with the Pacific coast. During its prevalence, a strong wind from the west and north-west, accompanied by a slight fall of snow has also prevailed. At Boone, Iowa, on the line at the Chicago and North-western Rail way, the switch-board was enveloped in a sheet of flame. In Minnesota, the telegraph wires were down all Wednesday.
    No warning ominously heralds the approach of these electric storms, and their departure is equally abrupt and unexpected. They come without any apparent change in the external condition of the temperature or weather--approaching and vanishing in obedience to a law as yet beyond human comprehension--irritating the operator, perplexing the philosopher, hindering journalists, and annoying the public generally.