who invented the sixth one?
Christiaan Huygens
Pendulum clock
From its invention in 1656 by Christiaan Huygens, inspired by Galileo Galilei, until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. 
who invented the first mechanical clock in 1300 Catholic monks which of the earliest civilizations used timekeeping devices? Hunter-gatherers, Prehistoric Europe, Mesoamericans, etc why did the monks invent the clock? To regulate daily prayer- and work-schedules strictly and to ensure accuracy can you give me examples of timekeeping devices? Astronomical bodies, sticks and bones to track the phases of the moon or the seasons, Stone circles, sexagesimal timekeeping, and vigesimal counting system name some of the innovations during the medieval period Clock, wristwatches, Clock of the Long Now, mechanical clock, and pendulum clock did ancient egypt use timekeeping devices? Yes, Shadow clocks and Sundials what about greece? They used water clocks, or clepsydrae, and water-based alarm clock name some of the innovations during the pre-modern period Mechanical clocks and pendulum clock is it possible to keep track of time underwater? Yes, by Marine chronometers how did the persians keep track of time? By using water clocks what device did the chinese invent to keep track of time? Outflow and inflow clepsydra is there an industry now that deals specifically with time keeping devices? Yes, clock and watch-making industry who invented the wristwatch? UNANSWERABLE what are the different types of clocks? Sundial, hourglass, water clocks, striking clock, watches, pendulum clock, and electric clock how does the first one work? It uses the Sun's altitude or azimuth (or both) to show the time. who invented the second one? Its origin is unclear how does the fourth one function? Works under the rack and snail striking mechanism
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Pendulum clock [SEP] Introduction
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a harmonic oscillator: it swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates. From its invention in 1656 by Christiaan Huygens, inspired by Galileo Galilei, until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Throughout the 18th and 19th centuries pendulum clocks in homes, factories, offices and railroad stations served as primary time standards for scheduling daily life, work shifts, and public transportation, and their greater accuracy allowed for the faster pace of life which was necessary for the Industrial Revolution.