https://en.m.wikipedia.org/wiki/Optical_telegraph https://en.m.wikipedia.org/wiki/Optical_telegraph One of the major recurring themes of r/discworld is that so

https://en.m.wikipedia.org/wiki/Optical_telegraph https://en.m.wikipedia.org/wiki/Optical_telegraph One of the major recurring themes of r/discworld is that so much of the amazing ideas in Discworld were actually real things.