I Can’t Sleep - Clocks | Can’t Sleep? Learn About the History of Time

Episode Date: June 24, 2026

Clocks have shaped the way humans understand and organize time for thousands of years. This episode explores the history of timekeeping, from ancient sundials and water clocks to early mechanical devices designed to track the passing hours. Along the way, you’ll hear about inventors, astronomical observations, clockmaking traditions, and the surprisingly long quest to measure the passing of time with greater and greater accuracy. It’s steady and consistent, with no whispering and no sudden changes, just enough to give your mind something to follow as you wind down. Happy sleeping! Read with permission from Clock, Wikipedia (https://en.wikipedia.org/wiki/Clock), licensed under CC BY-SA 4.0. — Ad-free episodes: ⁠icantsleep.supportingcast.fm⁠Have a topic in mind? ⁠Request a topic⁠ Learn more about your ad choices. Visit ⁠megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices

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Welcome to the I Can't Sleep Podcast, where I help you drift off one fact at a time. I'm your host, Benjamin Boster. And today's episode is about clocks. A clock or chronometer is a device that measures and displays time. The clock is one of the oldest human inventions. meeting the need to measure intervals of time shorter than the natural units, such as the day, the lunar month, and the year. Devices operating on several physical processes have been used over the millennia.

Some predecessors to the modern clock may be considered clocks that are based on movement in nature. A sun dial shows the time by displaying the position. position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the hourglass. Water clocks, along with sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks, around 1,300 in Europe. kept time with oscillating timekeepers, like balance wheels.

Traditionally in orology, the study of timekeeping, the term clock was used for a striking clock, while a clock that did not strike the hours audibly was called a timepiece. This distinction is not generally made any longer. Watches and other timepieces that can be carried in one's person are usually not referred to as clocks. Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, clockmaking flourished.

The next development and accuracy occurred after 1656 was the invention of the pendulum clock by Christiane Higgins. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise timekeeping for navigation. The mechanism of a timepiece with a series of gears, driven by a spring or weights, is referred to as clockwork. The term is used for a similar mechanism not used in a timepiece. The electric clock was patented in 1840,

and electronic clocks were introduced in the 20th century, becoming widespread with the development of small battery-powered semiconductor devices. The timekeeping element in every modern clock is a harmonic oscillator, a physical object resonator that vibrates or oscillates at a particular frequency. This object can be a pendulum, a balance wheel, a tuning fork, a quartz crystal, or the vibration of electrons and atoms as they emit microwaves. The last of which is so precise that it serves as the formal definition of the second. Clocks have different ways of displaying the time.

Analog clocks indicate time with a traditional clock face and moving hands. Digital clocks display a numeric representation of time. Two numbering systems are in use, 12-hour time notation, and 24-hour notation. Most digital clocks use electronic mechanisms and LCD, LED, and VFD displays. For the blind and for use over telephones, speaking clocks state the time audibly in words. There are also clocks for the blind that have done. displays that can be read by touch. The word clock derives from the medieval Latin word for bell, clocka, and has cognates in many European languages.

Clock spread to England from the low countries, so the English word came from the middle low German and middle Dutch, clocka. The word is also derived from the middle English clock, old North French clock or Middle Dutch Clocker all of which mean bell the apparent position of the sun and the sky changes over the course of each day

reflecting the rotation of the earth shadows cast by stationary objects move correspondingly so their positions can be used to indicate the time of day a sun dial shows the time by displaying the position of a shadow on a usually flat surface that has markings that correspond to the hours. Sundials can be horizontal, vertical,

or in other orientations. Sundials were widely used in ancient times. With knowledge of latitude, a well-constructed sundial can measure local solar time with reasonable accuracy within a minute or two. sundials continued to be used to monitor the performance of clocks until the eighteen thirties when the use of the telegraph and trains standardized time and time zones between cities many devices can be used to mark the passage of time without respect to reference time time of day hours minutes etc and can be useful for measuring duration or intervals examples of such duration timers are candle clocks incense clocks and the hourglass both the candle clock and the incense clock work on the same principle

wherein the consumption of resources is more or less constant allowing reasonably precise and repeatable estimates of time passages in the hourglass fine sand pouring through a tiny hole at a constant rate indicates an arbitrary predetermined passage of time the resource is not consumed but reused water-clogs along with sundials are possibly the oldest time measuring instruments with the only exception being the day counting tally stick given their great antiquity where and when they first existed is not known and is perhaps unknowable The bull-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and Egypt around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, write about water clocks appearing as early as 4,000 BC in these regions of the world. The Macedonian astronomer Andronikos of Cyrus supervised the construction of the Tower of the Winds in Athens in the first century BC, which housed a large klepsidra inside as well as multiple prominent sundials outside,

allowing it to function as a kind of early clock tower. The Greek and Roman civilizations advanced water clock design with improved accuracy. These advances were passed on through Byzantine and Islamic times, eventually making their way back to Europe. Independently, the Chinese developed their own advanced water clocks by 725 AD, passing their ideas on to Korea and Japan. Some water-clock designs were developed independently, and some knowledge was transferred through the spread of trade.

Pre-modern societies do not have the same precise timekeeping requirements that exist in modern industrial societies, where every hour of work or rest is monitored, and work may start or finish at any time, regardless of external conditions. Instead, water clocks in ancient societies were used mainly for astrological reasons. These early water clocks were calibrated with a sundial. While never reaching the level of accuracy of a modern timepiece, the water clock was the most accurate and commonly used timekeeping device for millennia, until it was replaced by the more accurate pendulum clock in 17th century Europe.

Islamic civilization is credited with further advancing the accuracy of clocks through elaborate engineering. In 797 or possibly 801, the Abbasid Caliph of Baghdad, Harun or Rashid, presented Charlemagne with an Asian elephant named Abul Abbas. Together with a particularly elaborate example of a water clock, Pope Sylvester II introduced clocks to northern and western Europe around 1,000 AD. The first known geared clock was invented by the great mathematician, physicist, and engineer Archimedes during the 3rd century BC. Archimedes created his astronomical clock, which was also a cuckoo clock with birds singing and moving every hour. It is the first carillon clock as it plays music simultaneously,

with a person blinking his eyes, surprised by the singing birds. The Archimedes' clock works with a system of four weights, counterweights, and strings, regulated by a system of floats in a water container, with siphons that regulate the automatic continuation of the clock. The principles of this type of clock are described by the mathematician and physicist hero, who says that some of them work with a chain that turns a gear in the mechanism. Another Greek clock probably constructed at the time of Alexander was in Gaza, as described by a Procopius.

The Gaza clock was probably a meteoroscopaean, i.e. a building showing celestial phenomena and the time. It had a pointer for the time and some automations similar to the Archimedes clock. There were twelve doors opening one every hour, with Hercules performing his labors, the lion at nine o'clock, etc. And at night a lamp becomes visible every hour, with 12 windows opening to show the time.

The Tang Dynasty, Buddhist monk, Yishin, along with government official Leon Lingzang, made the escapement in 723 or 725 to the workings of a water-powered armillary sphere and clock drive, which was the world's first clockwork escapement, the Song Dynasty, Polymath, and genius, Su-Song incorporated it into his monumental innovation of the astronomical clock tower of Kaifung in 1088. His astronomical clock and rotating armillary sphere still relied on the use of either flowing water during the spring, summer, and autumn seasons, or liquid mercury during the freezing temperatures of winter. In Su-sung's water wheel, link-work device, the action of the escapements, arrest, and release, was achieved by gravity exerted periodically as a continuous

flow of liquid-filled containers of a limited size. In a single line of evolution, Su-Song's clock therefore united the concepts of the Clipsidra and the mechanical clock into one device run by mechanics and hydraulics. In his memorial, Su-Song wrote about this concept. according to your servant's opinion there have been many systems and designs for astronomical instruments during past dynasties all differing from one another in minor respects but the principle of the use of water-power for the driving mechanism has always been the same the heavens move without seizing but so also does water flow and fall thus if the water is made to pour with perfect evenness and the comparison of the rotary movements of the heavens and the machine will show no discrepancy or contradiction for the unresting follows the unceasing song was also strongly influenced by the earlier armillary sphere created by jong syshune nine seventy six a d who also employed the escapement mechanism and used liquid mercury instead of water in the water wheel of his astronomical clock tower.

The mechanical clockworks of Sioux Song's astronomical tower featured a great driving wheel that was 11 feet in diameter, carrying 36 scoops into each of which water was poured at a uniform rate from the constant level tank. The main driving shaft of iron with its cylindrical nymphs, necks, supported on iron crescent-shaped bearings, ended in a pinion which engaged a gear wheel at the lower end of the main vertical transmission shaft. The great astronomical hydro-mechanical clock tower was about ten meters high, featured a clock escapement, and was indirectly powered by a rotating wheel, either with falling water or liquid mercury. A full-sized working replica of

Su Song's clock exists in the Republic of China National Museum of Natural Science, Tai Chung City. The full-scale, fully functional replica, approximately 12 meters in height, was constructed from Su-sung's original descriptions and mechanical drawings. The Chinese escape, spread west and was a source for Western escapement technology. In the 12th century, Al-Ghizari, an engineer from Mesopotamia, who worked for the Artucat king of Diyah Bakr, Nassir al-Din, made numerous clocks of all shapes and sizes. The most reputed clocks include the elephant, scribe, and castle clocks,

some of which have been successfully reconstructed. As well as telling the time, these grand clocks were symbols of the status, grandeur, and wealth of the Urtuk state. Knowledge of these mercury escapements may have spread through Europe with translations of Arabic and Spanish text. The word horologia was used to describe early mechanical clocks, But the use of this word for all timekeepers conceals the true nature of the mechanisms. For example, there is a record that in 1176, Saint Cathedral in France installed an orologue.

But the mechanism used is unknown. According to Jocelyn de Bracolon in 1198, during a fire at the Abbey of St. Edmundsbury, The monks ran to the clock to fetch water, indicating that their water clock had a reservoir large enough to help extinguish the occasional fire. The word clock, which gradually supersedes orologge, suggests that it was the sound of bells that also characterized the prototype mechanical clocks that appeared during the 13th century in Europe. In Europe between 1280 and 1320, there was an increase in the number of references to clocks and horologes and church records, and this probably indicates that a new type of clock mechanism has been devised. Existing clock mechanisms that used water power were being adapted to take their driving power from falling weights. This power was controlled by some form of oscillating mechanism,

probably derived from existing bell ringing or alarm devices. This controlled release of power, the escapement, marks the beginning of the true mechanical clock, which differed from the previously mentioned cogwheel clocks. The verge escapement mechanism appeared during the surge of true mechanical clock development, which did not need any kind of fluid power like water or mercury to work these mechanical clocks were intended for two main purposes for signaling and notification and for modeling the solar system the former purpose is administrative the latter arises naturally given the scholarly interests in astronomy science and astrology and how these subjects integrated with the religious philosophy of the time.

The astrolabe was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce a working model of the solar system. Simple clocks intended mainly for notification were installed in towers and did not always require faces or hands. they would have announced the canonical hours or intervals between set times of prayer. Canonical hours varied in length as the times of sunrise and sunset shifted. The more sophisticated astronomical clocks would have had moving dials or hands

and would have shown the time in various time systems, including Italian hours, canonical hours. canonical hours, and time as measured by astronomers at the time. Both styles of clocks started acquiring extravagant features, such as automata. In 1283, a large clock was installed at Dunstable Priory in Bedfordshire and Southern England. Its location above the rude screen suggests that it was not a water clock. In 1292, Canterbury Cathedral installed a great horloge. Over the next 30 years, there were mentions of clocks at a number of ecclesiastical institutions in England,

Italy, and France. In 1322, a new clock was installed in Norwich, an expensive replacement for an earlier clock installed in 1273. This had a large two-meter of a large two-meter of a large two-meter astronomical dial with automata and bells. The costs of the installation included the full-time employment of two clockkeepers for two years. An elaborate water clock, the cosmic engine, was invented by Su Song, a Chinese polymath, designed it constructed in China in 1092. This great astronomical hydromechanical clock tower was about 10 meters high. and was indirectly powered by a rotating wheel with falling water and liquid mercury,

which turned an armillary sphere capable of calculating complex astronomical problems. In Europe there were the clocks constructed by Richard de Wollingford and Albans by 1336 and by Giovanni de Dundi in Padua from 1348 to 1364. they no longer exist but detailed descriptions of their design and construction survive and modern reproductions have been made they illustrate how quickly the theory of the mechanical clock had been translated into practical constructions and also that one of the many impulses to their development had been the desire of astronomers to investigate celestial phenomena. The Astrarium of Giovanni Dondi del Oloroggio was a complex astronomical clock, built between 1348 and 1364 in Padua, Italy, by the doctor and clockmaker Giovanni Dondi del Rhojo. The Astrarium had seven faces and 107 moving gears.

It showed the positions of the sun, the moon, and the five planets then known, as well as religious feast days. The Astrarium stood about one meter high and consisted of a seven-sided brass or iron framework, resting on seven decorative paw-shaped feet. The lower section provided a 24-hour dial and a large calendar drum, showing the fixed feasts of the church, the movable feasts, and the position in the zodiac of the moon's ascending node. The upper section contains seven dials, each about 30 centimeters in diameter, showing the positional data from the Prima Mobile, Venus, Mercury, the moon,

Saturn, Jupiter, and Mars. Directly above the 24-hour dial is the dial of the premium mobile, so-called because it reproduces the diurnal motion of the stars and the annual motion of the sun against the background of stars. Each of the planetary dials used complex clockwork to produce reasonably accurate models of the planet's motion. These agreed reasonably well, both with Ptolemaic theory and with observations. Wallingford's clock had a large astrolabe-type dial, showing the sun, the moon's age, phase, and node, a star map, and possibly the planets.

In addition, it had a wheel of fortune and an indicator of the state of the tide at least. London Bridge. Bells rang every hour, the number of strokes indicating the time. Dundee's clock was a seven-sided construction, one meter high, with dials showing the time of day, including minutes, the motions of all the known planets, an automatic calendar of fixed and movable feasts, and an eclipse prediction hand-rotating once every. 18 years. It is not known how accurate or reliable these clocks would have been. They were probably adjusted manually every day to compensate for errors caused by wear and in precise manufacture. Water clocks

are sometimes still used and can be examined in places such as ancient castles and museums. The Salisbury Cathedral Clock built in 1386 is considered to be used. the world's oldest surviving mechanical clock that strikes the hours. Clockmakers developed their art in various ways. Building smaller clocks was a technical challenge, as was improving accuracy and reliability. Clocks could be impressive showpieces to demonstrate skilled craftsmanship, or less expensive, mass-produced items for domestic use. The escapement in particular was an important factor affecting the clock's accuracy, so many different mechanisms were tried. Spring-driven clocks appeared during the 15th century, although they are often erroneously credited to Nuremberg watchmaker Peter Henline, around 1511.

The earliest existing spring-driven clock is the chamber clock given to Philip the good. Duke of Burgundy, around 1430. Now in the Germanicius National Museum, spring power presented clockmakers with a new problem, how to keep the clock movement running at a constant rate as the spring ran down. This resulted in the invention of the Stackfried and the fusee in the 15th century, and many other innovations down to the invention of the modern going barrel in 1760. Early clock dials did not indicate minutes and seconds.

A clock was a dial indicating minutes was illustrated in a 1475 manuscript by Paulus Almanus, and some 15th century clocks in Germany indicated minutes and seconds. An early record of a second's hand on a clock dates back to about 1560, on a clock now in the Fremer's Dorff collection. During the 15th and 16th centuries, clockmaking flourished, particularly in the metalworking towns of Nuremberg and Augsburg, and in Blas, France. Some of the more basic table clocks have only one timekeeping hand, with a dial between the hour markers being divided into four equal parts,

making the clocks readable to the nearest 15 minutes. Other clocks were exhibitions of craftsmanship and skill, incorporating astronomical indicators and musical movements. The cross-speed escapement was invented in 1584 by Jost Berge, who also developed the remandoir. Berge's clock was a great improvement in accuracy, as they were correct to within a minute a day. These clocks helped the 16th century astronomer Tycho Brahe to observe astronomical events with much greater precision than before. The British had dominated watch manufacture for much of the 17th and 18th centuries,

but maintained a system of production that was geared towards high-quality products for the elite. Although there was an attempt to modernize clock manufacture with mass production technique, and the application of duplicating tools and machinery by the British watch company in 1843. It was in the United States that this system took off. In 1816, Eli Terry and some other Connecticut clockmakers developed a way of mass-producing clocks by using interchangeable parts. Aaron Lufkin Denison started a factory in 1851 in Massachusetts that also used interchangeable parts, and by 1861 was running a successful enterprise incorporated as the Waltham Watch Company.