Flame-based telegraphy, Ancient Greece. This system was described by Ancient Greek historian and scholar Polybius in around 150 BC. It was a system of communication using a series of torches to indicate letters of the alphabet. Ten torches and two walls were used to spell out words by their constituent letters according to a grid of coordinates. One torch on the left and three on the right, as seen, might indicate a certain letter of the alphabet. A visual sighting platform between the walls is used to observe the signals. Artwork from 'Electricite' (1911) by Max de Nansouty, part of the 'Les merveilles de la science' series of 1867-1891 by Louis Figuier.