where did the 24 hour clock come from
24-hour clock The 24-hour time system has its origins in the Egyptian astronomical system of decans, and has been used for centuries by scientists, astronomers, navigators, and horologists. In East Asia, time notation was 24-hour before westernization in modern times. Western-made clocks were changed into 12 dual-hours style when they were shipped to China in the Qing dynasty. There are many surviving examples of clocks built using the 24-hour system, including the famous Orloj in Prague, and the Shepherd Gate Clock at Greenwich.[citation needed]