The Fire Alarm Telegraph: The Box That Called the Engines Radio's first practical detector was a tube of filings that heard sparks and forgot them when tapped. This guide explains the coherer and its decade of service. Quick facts Discovered Branly, 1890 Demonstrated Lodge, 1894 Mechanism filings cohere Reset automatic tapper Succeeded by crystal + magnetic Marconi's early receivers printed ship and shore traffic through the coherer, tapper and inker working in rhythm. Within ten years steadier detectors arrived - but wireless telegraphy's first decade was copied, quite literally, through dust. Start here: https://morsecodeworks.com/ Morse Code Works - free Morse code tools and guides. Reference chart