11.07.2019 in Review

History of Clocks

The history of clocks is an integral part of cultural history closely connected with the progress of science and technology. Historically, the improvement of methods and tools for measuring time did not happen spontaneously. It occurred under the influence of the accuracy required for measuring time at a given level of development of culture and civilization. The requirements for accuracy in measurement increased along with the level of civilization development. In this regard, the use of science and technology gained increasing importance since measuring time was impossible without further improvement of methods and tools. The history of clocks aims to trace the historical development of methods and tools for measuring time from the earliest sundial to the modern smartwatch.

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The regular changes of seasons, day and night, and the movement of the sun and the moon across the sky suggested the first primitive concepts for the measurement of time (day, morning, noon, afternoon, evening, and night) to ancient people. Over time, the methods of measuring time were gradually improved. People used the calendar time-measuring method for a long period, counting the number of expired or upcoming days. Primitive devices for timing included a strap with small knots or a plank with notches. One could have counted the number of days elapsed by making a notch every day. Alternatively, one could have determined the number of days remaining to some expected event by untying the knot.
Over time, these methods became obsolete. The movement of the sun formed the basis of the sundial, which appeared about 5,500 years ago. A simple sundial represents a thin and tall object, also known as gnomon, and a specially prepared surface that the gnomon casts a shadow on. During the day, the shadow of the gnomon moves and shows the time, crossing the time marks on the surface. The angle of the upper part of the gnomon depends on the latitude of the place, while the gnomon’s directions rely on the polar star, parallel to the axis of the earth.
Using sundial, one can determine the time to the nearest hour. Of course, the use of such a clock was possible only during the daytime hours. First gnomons were complex architectural structures in the form of high obelisks, covered by a half-circle of stone pillars, which were the benchmarks for determining the time. Then, sundial became better: they reduced in size and got a dashed scale. There were even pocket sundials. Many of the early sundials lasted a long time until newer and more comfortable models appeared. Attempts to measure nighttime led to the creation of candle and incense clocks.

Candle and Incense Clocks

The candle clock represented a thin candle of about one meter with a scale along its entire length. It indicated the time with relative accuracy and even illuminated the houses of church and secular dignitaries. The sides of the candle sometimes had metal studs that fell as the candle burned out. The contact of metal studs with the metal cup of the candlestick was a kind of sound alarm of time.
The incense clock represented a stick made of special types of wood crushed into powder. The wood was mixed with incense, and the result was rolled into the sticks of different shapes (often spiral). This structure ensured a uniform combustion. The sticks could have burned for months, requiring no maintenance. The disadvantage of such clocks was the unprofitability of their use during the daytime. In addition, the accuracy of their indications was low because of the different speed of burning of various incenses in different lamps and candles. As a result, the candle and the incense clocks were replaced by the water clock.

Water Clock

The water clock was the most important type of the simplest forms of the clock. These clocks reliably worked during the day and night. Their structure was quite simple: a vessel with a hole at the bottom and time marks on the walls, which allowed a person to follow the fall of the water level. The vessel was made usually of metal, clay, or glass, and filled with water which slowly ran out, drop by drop. The water clocks quickly became popular. They were used at home, by the armed forces, government agencies, and schools. They were on the racetracks, stadiums, and in judicial institutions.
The water clock was also known as clepsydra. This name comes from the combination of two Greek words kleptein ‘to steal’ and idor ‘water’. In ancient Greece, people used the water clocks to regulate the time allocated to speakers during trials. The clocks looked like a large amphorae, the inner surface of which had a shape formed by the rotation of parabola or ellipsoid. The amphora’s height was about 1 m, and a width was more than 40 cm. It accommodated about 100 liters of water, which took almost 10 hours to empty the vessel completely. The water had a float with a long rod attached to it. The rod had an engraved scale. The time elapsed after the start of the outflow of water was indicated on the scale. A float went down in amphora evenly since the reduction of the excessive velocity was induced by the decreasing inner diameter of the vessel.
The most highly developed clepsydrae were in the richest trading city of Egypt, Alexandria. The world’s first clock workshop that produced a variety of clepsydrae was opened in Alexandria. The masters of automatic water clocks, which were called the artisans, were engaged in the production of clepsydrae. Most Alexandria’s clepsydrae represented a complex automatic device equipped with a variety of signaling mechanisms and moving figures, which produced a variety of motions at a certain hour. The interest in the water clocks increased from this point since the clock acquired the entertaining function. The Eastern Roman Empire developed technical and cultural traditions of antiquity, and automatic water clocks served as a decoration of many rooms of the imperial palace in Constantinople.
The fact that the clepsydra was not dependent on the sun’s light made this device suitable for the continuous measurement of time at any part of the day. Moreover, it made the development of some mechanical elements possible. The competition in the invention of ingenious hydraulic and pneumatic mechanisms began. The hands of talented masters made many outstanding works of high artistic value and functionality.


The date of appearance of the first hourglass, or sand clock, is unknown. However, it appeared not earlier than the transparent glass. It is believed that the Western Europe learned about the hourglass only at the end of the Middle Ages. One of the oldest mentions of them is the message from 1339 found in Paris. It provided guidance on the preparation of fine sand sifted powder of black marble, boiled in water and dried in the sun. Despite the fact that the hourglass appeared in Europe so late, it spread quickly. This is due to its simplicity, reliability, low price, and the ability to measure time at any moment of the day or night. The disadvantage was a comparatively short time interval that could be measured without upturning the device. The ordinary hourglass was designed to measure half an hour or an hour, less often 3 hours. The huge hourglass of the 12-hour course was built in very rare cases.
As well as the candle and incense clocks, the hourglass never reached the accuracy of the water clock and sundial. Furthermore, the prolonged use of hourglass changed its accuracy because sand grains fragmented gradually into smaller ones, and the hole in the middle of the diaphragm, on the contrary, increased gradually. The imperfection of the hourglass led to the emergence of a completely new type of clock.

Mechanical Clock

Solar, water, and fire chronometric instruments completed the first phase in the development of instruments for measuring time. Gradually, people developed a clearer understanding of the time and began working on better ways to measure it. A revolutionary invention that marked a completely new stage of development in this direction was the creation of the first mechanical clock, which gave rise to the modern era of timekeeping.
Mechanical clock appeared in the 14th century. It was a huge heavy mechanism of tower clock which was driven by a weight suspended on a rope to the drive shaft of the mechanism. The escapement of this clock was the so-called spindle, which represented a rocker arm with heavy loads fixed on a vertical axis and driven alternately to the right and left, causing rotation. The inertia of loads exerted an inhibitory effect on the clock mechanism, slowing the rotation of the wheels. The accuracy of the clock with spindle control was low, and the daily error was more than 60 minutes.
The discovery of the laws of oscillation of the pendulum was of great importance for the further improvement of the clock. Galileo Galilei, who created the idea of a mechanical pendulum clock, discovered these laws. The actual construction of such clocks started in 1658 due to the talented Dutch inventor and scientist Christian Huygens. He also invented a balance spring, which allowed to create a pocket watch and wristwatches. Moreover, their fundamental structural scheme remained almost unchanged in the current clocks.
The first pocket watch appeared in 1500 after the invention of clockwork springs by Nuremberg watchmaker Peter Henlein. However, this first pocket watch had low accuracy. Only after the invention of the balance, pocket watch has become a precise and functional item from the trendy, expensive, and useless toy.
The 17th century was the time of the rapid development of watchmaking. Since the invention of the spiral spring, the torsion pendulum completely replaced the ordinary one in the wearable clock. After the implementation of the horizontal anchor escapement, the accuracy of the wearable clock has increased significantly. This fact led to the need to add a mechanism of a minute hand and a second hand later.
The clock mechanism became more complicated, and its accuracy increased with the development of science. At the beginning of the 18th century, the ruby and sapphire were used for the first time for the balance, and this fact improved the accuracy, power reserve, and reduced the friction. Gradually, pocket watches were supplemented with the increasingly complex devices. Some samples had a perpetual calendar, self-winding, an independent stopwatch, thermometer, power reserve indicator, minute repeater, and others. The back cover made of rock crystal made it possible to see the functioning of the mechanism.
The greatest achievement in the watch industry is the invention of the tourbillon by Abraham Louis Breguet in 1801. Tourbillon is a mechanical device designed to improve the accuracy of the clock by compensating the effects of gravity on the pallet fork. It also improves the even distribution of the grease of friction surfaces of the mechanism in the case of changing the vertical and horizontal position of the mechanism. Tourbillon is one of the most impressive mechanisms of the contemporary watches. Only skilled craftsmen can make such a mechanism, and the firm’s ability to produce tourbillon is a sign of its belonging to the clockwise elite. Therefore, Breguet succeeded in solving one of the biggest problems of the clockworks of his time: he found a way to overcome gravity.
Further, the mechanical clock has not undergone significant changes. The history of the clock has taken a new turn since the advent of the digital clock.

Digital Clock

Digital clock is a clock that uses periodic fluctuations of the electronic generator that are converted into the digital signals, which recur after one second, one minute, one hour, and so on. The signals are displayed on a digital display that shows the current time. In addition, some models show the day, month, year, and day of the week as well.
The sufficiently high accuracy of the electronic clock compared with the mechanical clock and the further development of microelectronics has led to the almost complete exclusion of the mechanical clock by the end of the 20th century from the life of a man. Gradually, an electronic alarm clock began to be integrated into various appliances and devices, allowing a person to manage them (enable or disable) upon the occurrence of a certain time. Digital watches have become an indispensable element of devices such as VCRs, computers, and cell phones. Digital cameras and TVs have a built-in clock, but they usually are not intended to indicate the time.
The electronic clock can have its own display, mainly LCD in models with galvanic cells battery, or a vacuum fluorescent display in models powered by the power socket. In computers, electronic watches are part of the motherboard and can be adjusted via BIOS or OS. They use a battery mounted on the motherboard for smooth operation at the time when the computer is turned off. The electronic clock is also used in vehicles. These watches have a luminous display, which can be seen at any time, and are often powered by the battery of the vehicle.

Atomic Clock

Nuclear physicists have given new impetus to the development of devices for the measurement of time. The atomic clock is a device for measuring time, which uses its own fluctuations associated with the processes occurring at the level of atoms and molecules. The first atomic clock was built in 1949.
Atomic clocks are crucial in navigation. Determination of the position of spacecraft, satellites, ballistic missiles, aircraft, submarines, and the movement of vehicles in automatic mode via satellite (GPS, GLONASS, Galileo) is unthinkable without atomic clocks. Atomic clocks are also used in satellite and terrestrial telecommunications, including mobile base stations, international and national bureau of standards, and services of the exact time.
Scientists from different countries are working to improve the atomic clock and the national primary standards of time and frequency. The accuracy of such clocks has been increasing steadily. In addition, scientists are actively developing compact atomic clocks for the use in everyday life.


The history of smartwatch started almost immediately after the appearance of the first electronic watch. After about ten years since the emergence of the first electronic watch with LED display, the Japanese company Seiko launched electronic watches Seiko Data 2000 in 1982 that were equipped with a docking station with a keyboard. A user could have made different notes in the memory of the watch. After just two years, in 1984, Seiko released the following model, namely RC-1000 Wrist Terminal, which really could be called the full-fledged smartwatch at the time. This model had a terminal remote access to a PC and was compatible with computers of Apple, IBM, Commodore, and other companies. In 1985, the division of Seiko called Epson released the RC-20 Wrist Computer model, which had its own processor Zilog Z80 with 2 kB of RAM and 8 kB of internal memory to record and store data.
However, the problem of that time was that the engineers did not really know what functions the smartwatch should be able to have. Only in 1999, Samsung attempted to create something similar to the modern smartwatch. The SPH-WP10 model had a very unusual design. The gadget was more like a mobile phone with a watchstrap, rather than the watch. In 2001, Samsung showed a new smartwatch. It finally had a modern design and did not look like the phone. A year earlier, in 2000, IBM released the Linux Watch smartwatch with its own operating system, but they did not receive the expected popularity due to a very strange design. In 2003, Microsoft introduced their own product, digital clock with the Smart Personal Object Technology, which allowed a person to control various appliances and electronics. However, it did not become highly acclaimed as well. In 2009, Samsung attempted again to connect the phone to the watch by launching the S9110 model with a touchscreen.Once again, this attempt was unsuccessful because people did not understand why they should pay big money for a gadget with the features of a much cheaper phone.
The developers took a fresh look on smartwatches at the beginning of the post-PC era when it became possible to create not only tiny but also quite powerful electronic gadgets. Two years later, in 2011, Sony Ericsson released the Live View smartwatch, and Motorola released the first watch with the Android operating system. The latter had 600 MHz processor, 256 MB RAM, and 16 GB of internal memory. It was equipped with wireless data transmission modules: ANT +, BT4, Wi-Fi, and GPS, and was compatible with Android smartphones of virtually all manufacturers. It also became possible to access the Internet anywhere and anytime. Currently, the range of smartwatches is quite large. It is annually updated with new models.


The history of the clock can be traced from the sundial to the smartwatch. Sundial was a simple and reliable indicator of the time, but it had some serious disadvantages. Its work was dependent on the weather and was limited to the time between sunrise and sunset. The following chronometric instruments, such as the candle and incense clocks, water clock, and hourglass, had an artificial standard of the unit of time in the form of the interval required for inflow, outflow, or burning of a certain number of substances. Mechanics as a science in the Middle Ages was aimed at the creation and development of time measurement devices. For this reason, the first mechanical clock appeared in the 14th century. Subsequently, mechanics has initiated social progress which has revealed the digital clock and the atomic clock to the world. Currently, the smartwatch is the latest achievement in the sphere of time-keeping devices.

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