This article explores the development of clocks throughout the ages.
Time has always been important to civilisations throughout history, despite the fact that it is only now, in the modern age that we have come to some understanding of what time is.
The telling of time has always been important, particularly to our agricultural past, when identifying events such as what day on the calendar to plant crops or knowing how long left until nightfall, was crucial.
Our systems of telling the time have always been based around the movement of the Earth. A year is defined as a complete orbit of the Sun whilst a day is a single revolution of our planet.
This solar and lunar method of time telling is fundamental for the way we live our lives, there is no point on having a system of time that would allow days to drift in to nights and vice versa.
Time telling was very basic until the middle-ages when the first mechanical clocks appeared in Europe. Before this time basic water clocks, sundials and other rudimentary timers were the only method of keeping track of the hours as they past.
The first mechanical clocks were not very accurate and relied on a verge-and-foliot escapement (a gear system that advancing the gear train at regular intervals or 'ticks'), but soon new technologies such as the pendulum meant that clocks became ever increasingly accurate.
The next big step-forward in time-keeping came with the development of the crystal oscillator in the first part of the twentieth century. These new electronic clocks were far more accurate than their mechanical counter-parts as they relied on a vibrating crystal (often quartz) that oscillated when an electrical current was passed through.
Although clocks became smaller and more sophisticated, true accuracy would not be achieved until the development of atomic clocks in the 1950’s. The atomic clock used the resonance of individual atoms (in most cases caesium) which had such an exact oscillation of 9,192,631,770 every second that the International System of Units (SI) defined a second as that number of oscillations of the caesium atom.
In fact while electronic clocks may lose a second every week or so, atomic clocks will not lose a second within several millions of years.
This increased accuracy, however, has proved to cause some problems. Because of this accuracy it was soon discovered that the Earth’s rotation, that which we had based our system of time on for millennia was in not as accurate as our clocks.
Because of the gravity of the Earth’s moon, the Earth slows down gradually each year. while this slowing of the Earth’s spin is less than a second a year, if it wasn’t accounted for eventually day would slip into night and vice versa (albeit in several millennia) rendering a system of time useless.
The only solution has been to include extra seconds every year or so on to the International Timescale (known as UTC or Coordinated Universal Time). These Leap Seconds as they are called are seen by some as a fudge in keeping time accurate and they wish to abolish them while others (including the world’s astronomers) argue they are essential in keeping track of night and day.
There are plenty of ways of keeping accurate time; the best solution is to use a dedicated NTP server to receive a time signal from an atomic clock time transmission either via a radio signal or the GPS system. Dedicated wall clocks and Ethernet clocks are also available that can receive a time from an atomic clock.
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