"Time is money", so it is said, but the history of clocks is a long and fascinating one. Keeping track of time was one of mankind's earliest developments and it has come a very long way since antiquity.
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Early solutions included using shadows from the Sun and water clocks, but these proved unreliable for accurate timekeeping. Mechanical clocks appeared during the middle ages and the development of the pendulum clock would be the de facto timepiece for many hundreds of years.
Today thanks to quartz oscillators and atomic clocks, keeping time has become a very precise technology indeed.
In the following article, we'll take a quick tour through the history of clocks and stop off at some key moments. If you have the time why not read on?
Who invented clocks?
According to historical records and archaeological finds the first time keeping devices known was developed by the Ancient Egyptians. Called Shadow Clocks, they were able to divide the day into 12-hour periods and used some of their enormous obelisks to track the movement of the sun.
They were also able to develop the first example of water clocks which appear to have first been employed in the Precinct of Amun-Re. Water clocks were later adopted by the Ancient Greeks (called the Clepsydra), and the Zhou Dynasty also developed their own versions around the same time.
These early water clocks were simple devices consisting of a reservoir of water with a tiny hole cut into the bottom. This lets the water out at a steady rate and hours were marked off with lines inside the water reservoir.
Candle Clocks were another ancient timekeeping device that was used widely around the world from China to England and Mesopotamia. Timesticks were developed in places like India and Tibet and the hourglass (which was widely used throughout Europe) arose a little later.
Sundials were developed around this time too and provided a good estimate for the hour of the day - at least when it was sunny.
Many if not all of these early time-keeping devices had their inherent problems, however. Shadow Clocks and Sundials didn't work at night, water clocks were notoriously inaccurate as water flows at different rates depending on the ambient temperature.
Water also has the annoying habit of freezing in winter and evaporating during summer. What was needed was a timekeeping device that could overcome these problems. The answer, as it turned out, was to go mechanical.
The first escapements appear in around the 3rd Century BC in Greece. These were simple water-powered versions that were able to transfer rotational energy into intermittent motion.
The Chinese were able to develop a mercury version in around the 10th Century with the direct ancestors of mechanical cocks appearing in 11th Century Iran.
The first true mechanical clocks appeared in 14th Century Europe. These early mechanical clocks employed the verge escapement mechanism with a foliot or balance wheel for accurate timekeeping.
The first examples were truly huge devices and relied on the use of heavy-weights to drive the clock's hands. They were often built in tall towers and were able to keep relatively good time for long periods.
Most often only lost about 2 hours a day. Whilst that might sound very inaccurate today, they were cutting edge at the time.
Some can still be found today with some examples in England and France dating to the 14th Century. Many would prove to be exquisite works of art like the Prague Astronomical Clock.
Mechanical clocks would quickly prove their worth as being very reliable (for the time) and were the de facto timepiece until the development of the true pendulum clock in the late 17th Century by Christiaan Huygens. Galileo would show a little earlier, in 1581, that pendulums could be used to help keep clocks accurate so long as the pendulum was swinging.
With the invention of the mainspring in the 15th Century, clocks were able to go portable for the first time. They would gradually reduce in size until pocketwatches first began to appear in the 17th Century.
The invention of the balanced spring and addition to clock balance wheels in the mid 17th Century greatly improved timekeeping device accuracy. Despite these advancements, pendulum clocks remained one of the most accurate clock designs well into the 20th Century.
This was until the developed of quartz oscillators and atomic clocks in the post-war years.
Microelectronics began to appear in the 1960s and were first used in laboratories. These made quartz clocks more compact and much cheaper to manufacture and produce. By the 1980s they became the world's dominant timekeeping technology in both clocks and wristwatches.
Atomic clocks are far more accurate than any previous timekeeping device, and are used to calibrate other clocks and to calculate the International Atomic Time; a standardized civil system, Coordinated Universal Time, is based on atomic time.
How did they tell time before clocks?
Before the development of mechanical clocks, timekeeping devices were a lot more basic in design. Many ancient civilizations are known to have observed the motions of astronomical bodies and the sun to determine dates, times and seasons.
The very first calendars may have been devised during the last glacial period who used sticks and bones to track the phases of the moon for seasons.
Later megalithic structures were developed like Stonehenge in the United Kingdom and throughout Europe.
Methods of sexagesimal-timekeeping, now common in both Western and Eastern societies, first appear nearly 4,000 years ago in Mesopotamia and Egypt. Early devices included sundials and other shadow clocks of the period.
Mesoamericans similarly modified their usual vigesimal counting system when dealing with calendars to produce a 360-day year.
Who made the first pendulum clock?
One of the biggest innovations in clock design was made by Christiaan Huygens during the 1600s. Building on the work of Galileo, Huygens was able to develop the first pendulum clock in 1656.
He patented his device the same year and pendulums would become a passion of his for many years. This culminated in his famous 1673 book the Horologium Oscillatorium, which is regarded as one of the most important 17th-century works in mechanics.
One of the key developments in Huygen's clocks was the invention of the balance spring. There is some debate whether Huygens or Robert Hooke got there first, but Huygen's was able to successfully employ it in his pendulum clock designs.
His pendulum clock design was much more accurate than the existing verge and foliot clocks and was immediately popular, quickly spreading over Europe.
Despite this, it seems Huygens was not able to capitalize on his invention. Pierre Séguier refused him any French rights, and Simon Douw of Rotterdam copied the design in 1658.
The oldest known Huygens-style pendulum clock is dated 1657 and can be seen at the Museum Boerhaave in Leiden.