This is an automated archive made by the Lemmit Bot.

The original was posted on /r/todayilearned by /u/jacknunn on 2025-07-02 03:47:38+00:00.

Original Title: TIL recording sound on magnetic wires was used before magnetic tapes in the early 1900s, and use of magnetic wires persisted into the 1960s for recorders designed for stealth use, including one with a microphone disguised as a wristwatch