In Roussillon I found a sundial. The first sundials were created in 1500 BC by the ancient Egyptians. The Romans and Greek refined this in 200 BC. It is based on earths movement around the sun. The times are written on the base and the shade shades the correct time. At first I didn't know how it works but I look at the instructions and that made it clearer but now days you could just use your digital watch. Sundials are a bit large to carry round as you can see in the photo.