About Time: A History of Civilization in Twelve ClocksFor thousands of years, people of all cultures have made and used clocks, from the city sundials of ancient Rome to the medieval water clocks of imperial China, hourglasses fomenting revolution in the Middle Ages, the Stock Exchange clock of Amsterdam in 1611, Enlightenment observatories in India, and the high precision clocks circling the Earth on a fleet of GPS satellites that have been launched since 1978. Clocks have helped us navigate the world