The visual telegraph, a system of signaling over distances using visual signals, enjoyed a brief period of relevance in the 19th century, offering rapid communication before being supplanted by the telegraph and other electronic communications. The post discusses its historical context, technical operation, and eventual decline, emphasizing how innovation often displaces previous technologies. Comments on the post reference similar fictional systems, such as the 'clacks' in Terry Pratchett's Discworld, suggesting an ongoing interest in visual communication methods both in fiction and reality.