Optical telegraph

Optical telegraph was a system used a long time ago to send messages over long distances, kind of like texting or messaging on phones. The system used tall towers with two arms, one for each letter of the alphabet. At each tower, a person would use a telescope to look at the next tower in the direction of the message. They would then use the correct arm positions to send the message to the next tower by making sure the arm position matches the letter. For example, if they want to send the letter "A," they would put one arm up and one arm down. The person at the next tower would see the arm position through their telescope and know which letter was being sent. And then they would use the same signaling technique to send the message to the next tower. This way, people could send messages across many miles and over different terrains, like mountains or forests. It was a very important communication system before the invention of telephones and other electronic communication methods.