Electrical Telegraph: Acid Bubble Signals, Mercury Relays and Lorenz Codes

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In 1816 Francis Ronalds built an eight-mile underground telegraph in his garden using static electricity, and the British Admiralty rejected it as wholly unnecessary. Earlier, a 1753 letter in the Scots Magazine proposed 26 wires that made pith balls twitch, and in 1809 Samuel Thomas von Sömmerring sent current down as many as 35 wires into tubes of acid, reading letters from hydrogen bubbles. Volta's battery of 1800, Ørsted's deflected compass needle, William Sturgeon's electromagnet and Joseph Henry's bell rung through a mile of wire led to the relay of 1835, while Carl Friedrich Gauss and Wilhelm Weber strung two wires over Göttingen in 1833 and encoded letters as positive and negative pulses.

In 1837 William Fothergill Cooke and Charles Wheatstone built a five-needle system for the Great Western Railway, then dropped it for a single needle on overhead poles after buried insulation rotted. Samuel Morse and Alfred Vail recorded dots and dashes on paper tape and sent What hath God wrought in 1844. Gutta-percha, tested by Michael Faraday, insulated the 1850 Dover to Calais cable, the SS Great Eastern laid the Atlantic line in 1866, and by 1902 cables circled the globe. Faster machines followed, and Alexander Graham Bell's work on the harmonic telegraph led to the telephone, which Western Union dismissed as a toy before AT&T later bought its telex business.

• Operators learned to read Morse by the clicks of the stylus, so paper recorders gave way to the sounder.
• The 1851 Vienna Conference adopted Gerke's modified Morse code as a European standard.
• Émile Baudot's five-pulse code gave 32 combinations, and Creed teleprinters used compressed air to punch tape at 200 words a minute.
• Edwin Stanton ran the Union's 15,000 miles of wire straight into his War Department office.
• Cut cables pushed German Lorenz cipher traffic onto radio in World War II, where Bletchley Park intercepted and broke it.