History of Timekeeping

Water Clock

4000 BCE

The earliest evidence of the use of a water clock is in China. The water clock used the consistent flow of water through an openings to measure the passage of time

Shadow Clock

3000 BCE

Using an obelisk, Egyptians told time by measuring the shadow cast by the sun as it struck the pillar.

Rope Burning

1700 BCE

In the measuring of shorter lengths of time, the Chinese would burn lengths of rope which had equally spaced knots, measuring the time by the number of knots and rope that had been consumed.

Sundials

700 BCE

Potentially a much older technology than listed (perhaps 1500 BCE) the sundial measured the shadow cast by the sun off of the dial to track the passage of the day.

Candles as Clocks

520

The measuring of a candle and the amount of wax that had been melted was used to keep track of time. Different sized candles could be used to measure differing lengths of time.

Hourglass

1000

Originally very useful as it was one of the most reliable methods to tell time at sea, the hourglass used a consistent flow of sand between chambers to measure the passage of time. It could also be used as a timekeeper, kind of like a stopwatch.

Mechanical Clocks

1300

Using the principles of physics, these clocks measured more accurately the passage of time, being able to mark the passage of seconds, minutes hours, days, and years significantly better than past methods.

Watches

1400

A timepiece that could be easily carried, they used small coiled springs to progress the hands on the face.

Modern Quartz Clock

1927

Using the electrical properties of quartz crystals, the modern clock was born, becoming the base timing standard in the US until the 1960's.

Atomic Clock

1955

Considered to be the most reliable clock in use today, it measures the vibrations of the system of an element or molecule to accurately tell time down to the billionths of a second each year.

Pulsar Clock

2011

Those currently less accurate than an atomic clock, this clock depends on the counting of radio pulses emitted by a pulsar. This form of timekeeping has durability on it's side as a clock based on pulsars could tell time accurately for millennia.