This is a bump
and a slight diversion from the thread. In the pre-electric age, and before Samuel Morse and his code, there was optical telegraph. This Finnish stamp from 1979 (Facit #844) shows an optical telegraph tower near Eckero in the Aland Islands. Sweden constructed the towers from Grisslehamn, on its east coast, and in the Aland Islands for fast communication across the Gulf of Finland.
From the nationalstadsparken.se website, "Abraham Edelcrantz, private secretary to the king, introduced the optical telegraph into Sweden in 1794. Each signal station operated on ten collapsible shutters that could be set in two positions on high wooden scaffolding. In total, 1024 different signals could be sent. In many ways, the system anticipated the later binary alphabet for binary communications.