who came up with the 12 hour clock
12-hour clock The 12-hour clock can be traced back as far as Mesopotamia and Ancient Egypt.[4] Both an Egyptian sundial for daytime use[5] and an Egyptian water clock for night-time use were found in the tomb of Pharaoh Amenhotep I.[6] Dating to c. 1500 BC, these clocks divided their respective times of use into 12 hours each.
History of timekeeping devices During the Middle Ages, clocks primarily served religious purposes; the first employed for secular timekeeping emerged around the 15th century. In Dublin, the official measurement of time became a local custom, and by 1466 a public clock stood on top of the Tholsel (the city court and council chamber).[115] It was the first of its kind to be clearly recorded in Ireland, and would only have had an hour hand.[115] The increasing lavishness of castles led to the introduction of turret clocks.[116] A 1435 example survives from Leeds castle; its face is decorated with the images of the Crucifixion of Jesus, Mary and St George.[116]