A long and meandering essay about the history of measuring time
by Theodor Ringborg

Toril Johannessen’s piece Historical Time (2011) is a cubic clock with clock faces on all four horizontal sides, up a three-metre-tall pole in the outdoor atrium of the Faculty of the Humanities of the University of Bergen. Accompanying the piece are nine prints hung in corridors surrounding the atrium, which feature graphic amalgamations of diagrams showing the frequency of selected words in academic journals, heights of mountains and economical statistics of the percentage growth in gross domestic product. Although the clock looks like any other public clock, it follows an aberrant kind of time: rather than the customary 1 to 12 it runs from 1 to 10. It is thus obeying what is, aside from ‘decimal time’, called French Revolutionary Time, due to the decimalisation of France between 1793 and 1805, the period in which, along with the metric system, a new calendar was implemented that eradicated all royalist and religious influences. Each day in the new Republican Calendar was divided into ten hours, each hour, just as Johannessen’s clock, into one hundred decimal minutes, and each decimal minute into one hundred decimal seconds. An hour on a clock of this kind is 144 conventional minutes (more than twice as in a conventional hour), while a minute is 86.4 conventional seconds (44% longer than a conventional minute), and a second is 0.864 conventional seconds (13.6% shorter than a conventional second). During this partly arithmetic revolution in France clocks were manufactured to display decimal time, but it never really caught on and mandatory adherence to it was officially suspended on 7 April 1795. (01)

Looking at Johannessen’s clock, taking into account the accompanying prints, it seems to a lesser degree to explore the frequently seized existential question of time and heralds more the notion of horology, the science of measuring time. This clock, as it ticks out of synch from the rest, connotes an instance in the history of timekeeping prior to ubiquitous synchronisation and global standardisation. Despite what time might be, there are clocks that account for what time it is, and the history of the construction of time has had profound implications. Indeed, it is near impossible to speak about time without becoming slightly philosophical, but it is in this instance more about the mechanics, the measuring of time, no matter how concocted it might be thought to be. The history of horology is rich and it is certainly too extensive to comprehensively chronicle here, but it is not inconsequential to briefly trace, particularly when dealing with a piece like Historical Time. When we measure time today we adhere to a sexagesimal numeral system, which is equally dedicated to degrees and geographical coordinates, in turn revealing a curious alliance between the three. The earliest instances in the development of keeping time, alongside this structure, are found in ancient Babylonian water clocks. It is a system that, inherited and developed from the Sumerians, is by some cited to predicate our current approach of, for instance, sixty seconds in a minute. But despite these early water clocks featuring indicators that measured time, the gauges seem to have been variable. Tablets like the Enuma-Anu-Enlil, dated to between 1600 and 1200 BC, and the MUL.APIN, from the seventh century BC, refer to the function of measuring the flow of liquid in a jug, further mentioning payments of night and day guards. As the seasons changed, so did the length of a day and consequently time was measured with temporal hours, making time be expressed in the weight of water flowing and not as a perpetual sequence. As the historian of mathematical astronomy Otto Neugebauer describes it:

To define the length of a ‘night watch’ at the summer solstice, one had to pour two mana of water into a cylindrical clepsydra; its emptying indicated the end of the watch. One-sixth of a mana had to be added each succeeding half-month. At equinox, three mana had to be emptied in order to correspond to one watch, and four mana were emptied for each watch of the winter solstitial night. (02)

Without consistent indicators time isn’t evenly spaced, and, despite the historian Herodotus’s attribution of the invention of timekeeping to the Babylonians, the earliest timepieces that appear to count the course of time as continuous seem to derive from Egypt. Here we have the first recorded word for hour,  which we also know was counted as 24 in total, divided in a day and a night. From around 3500 BC, the devices used were ‘gnomons’, upright triangles that cast an inevitable shadow as the sun revolved around earth. But these evolved to what are called ‘shadow clocks’, which were more precise sundials and were in use from around 1500 BC. The principle is as simple as that of any sundial, but the great innovation was a modified, more precise gnomon that allowed for a more exact division of time. The shadow clock gnomon was made up of a long stem divided into six parts, as well as an elevated crossbar that cast a shadow over the marks. This kind of device is featured in one of the earliest known accounts of instruments for the measurement of time and recounts a divine intervention of the flow of time that also hints at the accuracy of the timepiece. In the Old Testament it says:

8 And Hezekiah said unto Isaiah: ‘What shall be the sign that the LORD will heal me, and that I shall go up unto the house of the LORD the third day?’ 9 And Isaiah said: ‘This shall be the sign unto thee from the LORD, that the LORD will do the thing that He hath spoken: shall the shadow go forward ten degrees, or go back ten degrees?’ 10 And Hezekiah answered: ‘It is a light thing for the shadow to decline ten degrees; nay, but let the shadow return backward ten degrees.’ 11 And Isaiah the prophet cried unto the LORD; and he brought the shadow ten degrees backward, by which it had gone down on the dial of Ahaz. (2 Kings 20:8-11)

As the development of timepieces in Egypt had progressed, so it had in Babylonia. And it is clear that this new knowledge transposed to the Hellenistic period and the Greeks, but it is uncertain who supplied them with the fundamentals of noting time. It stands to reason though that it was the Babylonians. Both historians Herodotus and Vitruvius attribute them with enlightening the Hellenes about the mechanics of the gnomon and the divisions of a day. Herodotus writes in the second book of The History of Herodotus: ‘For as touching the sun-dial and the gnomon and the twelve divisions of the day, they were learnt by the Hellenes from the Babylonians.’ Vitruvius, similarly, in his Ten Books on Architecture, refers to Berosos, a Babylonian writer, priest and astronomer active at the beginning of the third century BC as the inventor of a particular and influential hollowed out sundial. However, Vitruvius in the same book goes further, detailing the features of gnomons and sundials at length, explaining in depth their construction and function. A brief part reads:

Hence, wherever a sundial is to be constructed, we must take the equinoctial shadow of the place. If it is found to be, as in Rome, equal to eight ninths of the gnomon, let a line be drawn on a plane surface, and in the middle thereof erect a perpendicular, plumb to the line, which perpendicular is called the gnomon. Then, from the line in the plane, let the line of the gnomon be divided off by the compasses into nine parts, and take the point designating the ninth part as a centre, to be marked by the letter A. Then, opening the compasses from that centre to the line in the plane at the point B, describe a circle. This circle is called the meridian. (03)

The Hellenistic period into the Roman era propelled timekeeping forwards. While sundials and gnomons had so far been stationary, Theodosius of Bithynia invented a dial that could be used anywhere on earth in the second century BC, a remarkable and paradigmatic feat. Another instance that reveals the interest and need of the field is the Tower of Winds, which is believed to have been constructed by Andronicus of Cyrrhus about 50 BC: a structure that combines sundials, a water clock and a wind vane placed on the agora in Athens. The timepieces were, however, not used widely in society, although it might seem they were, with a giant clock on the town square. However, they were used chiefly as aids to fields like astronomy, and, as it was the water clock that could provide timekeeping without dependency on the sun, it was these devices that came to evolve the most. In time the water clocks became more and more advanced, as many parts of the world now depended on the keeping of time and therefore sought to perfect their function.

In China, candle clocks as well as incense clocks had developed, alongside water and sundial devices. Less is known about early Chinese timekeeping, but there are notations from around 200 BC about a modification in water clocks that compensated for the pressure that slowed timekeeping as the vessel filled. Furthermore, in 967, Zhang Sixun replaced water with mercury, allowing the fluid to remain unaffected by temperature differences. Following the sexagesimal systems development by the Babylonians, the Islamic parts of the world are, however, credited with the most significant progress and influence, developing an unprecedented accuracy with advanced engineering around the thirteenth century. An unconfirmed but often cited story is that of Harun al-Rashid, who gave Charlemagne one of the most advanced water clocks ever, the accounts of which vary greatly, but in which moving parts had been composed so balls dropped on a small drum every hour. It is not unlikely that the clock was astonishing. More corroborated instances of intricate clocks have been found. Most prominently in al-Jāmi bain al- ilm wa alamal al-nāfi fī inā at al- iyal (The Book of Knowledge of Ingenious Mechanical Devices) written in 1206 by the brilliant inventor al-Jazari. Here, among one hundred other mechanical inventions, he details what is known as the Elephant Clock, the first known clock with an automaton, which reacted after certain intervals of time. It was the first water clock to accurately record the passage of the temporal hours to match the uneven length of days throughout the year. The design, moreover, featured a variety of symbols for various cultures of the time; an Elephant is said to have represented African and Indian cultures, a dragon represented the Chinese, a phoenix the Egyptians and the water work the Greek, revealing intercontinental trade and perhaps also exchanges in clock making.

Water clocks remained the most accurate and common device for measuring time until the mechanical clock replaced them. It is not certain who exactly made the first mechanical clock and it is perhaps not that important. Clear enough is what allowed such a shift. It is called the ‘escapement’, and is a feature in a timepiece that alternately checks and releases the ‘train’, the rotating chain of gears, by a fixed amount and transmits a periodic impulse from the spring or weight to the balance wheel or pendulum. In fact, technically, an initial version was already in use in water clocks by the third century BC Greek engineer Philo of Byzantium. The first escapement that didn’t pertain to a water clock seems to be what is called a ‘verge escapement’. The origins of the verge are unknown and as the same name for clock, horologe, was used for both water and mechanical clocks at the time, there is no way of distinguishing the two in records. The verge, nevertheless, we know led to the first mechanical clocks, and more inventions that propelled time followed. If not being ‘first’, for instance, Jost Bürgi, a Swiss clockmaker, was nevertheless very early and aided the start of a new timekeeping era. He is said to have invented the minute hand on one of his clocks in 1584, by way of inventing the new ‘cross-beat escapement’. Furthermore, the ‘anchor escapement’, invented by the British polymath Robert Hooke, came to supersede the verge due to its improved accuracy and became the standard in pendulum clocks throughout the nineteenth century. And while over 350 other escapements carrying minutes and seconds were invented, some more successful than others, of all of them, the ‘grasshopper escapement’, invented around 1722, has come to bear the most significance.

This detailed chronology of timekeeping, although incomplete and almost certainly flawed, describes an emergence of the clock, the devise that made time appear to be better understood up to the point at which it was no longer dependent on its natural course. The nineteenth century saw for instance a distinction between Mean Solar Time and Apparent Solar Time, the difference being that Mean Time was constant while Apparent Time fluctuated with the sun. With the evolution of time keeping comes the notion of time and place being intrinsically linked. A detour to what unequivocally tied imaginary time with imaginary place is therefore necessary, because the history of accounting for time seems to invariably also be a history of accounting for place. Ptolomy, one of the first to draw imaginary lines that signified latitude and longitude on maps, relying on the previous work by the Greek geographer Marinos of Tyre, did so with the aid of time, setting latitude along the equator but preferring to note it as the length of the longest day, rather than degrees. For longitudes he writes, ‘it is appropriate to draw the meridians at intervals of a third of an equinoctial hour’, that is, at intervals of 5°.(04) It is for both types of lines thus a question of time, by way of a sexagesimal system, giving us the lines that circumnavigate the 360-degree earth. Even though the notion of latitudes and longitudes had since Ptolemy been perfected and better understood, the eighteenth century saw a time when the world was being conquered, territories were being colonised, wars were being waged and cargo was transported in ways previously unimaginable. Consequently, reliability of the whereabouts of ships became exceedingly important. The loss of thousands of men and valuable merchandise was often due to seafarers going about things a bit haphazardly. Fifteenth-, sixteenth- and seventeenth-century captains often relied on things like ‘dead reckoning’, which comes close to being a complete shot in the dark. There was no way of knowing the precise location of the vessel, due to the issue of the longitude.

The difference between latitudes and longitudes is quite simple, most obviously it lay in thedirectionality of the lines, but there is an additional difference that is a bit trickier. The zero degree parallel of the latitude is fixed by the laws of nature, while the zero-degree meridian of longitude isn’t. This makes it rather simple for anyone with a bit of experience to find latitudes by the length of the day, the height of the sun or the position of the stars. Longitudes, however, are much more dependent on time. To know one’s longitude at sea, one needs to know what time it is aboard the ship and also know the time at the home port or another place with a known longitude, at the same moment. The two clocks let the navigator divide the two times into geographical separation.(05) One hour of the earth’s 360-degree rotation is one twenty- fourth of a spin, which means 15 degrees east or west, depending on which way you are going. Founded on what seems to have been a largely capitalist ideal, since loosing cargo and men at sea was costly, the issue of navigation was pressing and thus the Longitude Act, a decree to solve the problem, was issued in Britain on 8 July 1714 with first-, second-, and third-place prize money, urging people from all sciences to find a solution. It wasn’t long, however, until ‘discovering the longitude’ became synonymous with attempting the impossible. The clocks of the time would indeed be carried out to sea, but since they were either based on pendulums, the movement to and fro of which sent time off rhythm on board a rocking ship, or escapements that had to be wound up and the metal of which eroded in sea air, none of these were reliable enough. Astronomy, the movement of stars and the moon hadn’t been perfected well enough either; particularly if one considers that being a mere one degree off longitude means to be off by about 110 kilometres, making you miss your mark quite significantly, or perhaps hit an island and sink, as was common. Some of the greatest minds advocated that the solution lay within astronomy rather than time. Newton wrote:

A good watch may serve to keep a recconing at sea for some days and to know the time for a celestial Observ[at]ion: and for the end a good Jewel watch may suffice till a better sort of Watch can be found out. But when the Longitude at sea is once lost, it cannot be found again by any watch. (06)

By this Newton meant that the most reliable and probable solution to the problem was to be found in the heavenly bodies, and not by means of any clock, although it is precisely within the keeping of time that the solution came to be found.

John Harrison was a certain kind of genius, who without formal training and after a series of advanced clock oriented inventions turned his attention to the longitude and the prize. Constructing a total of five clocks that took up the challenge, Harrison’s inventions cannot be underestimated. With, among others, the grasshopper escapement there was a total change of time’s rhythm. His first attempt took five years to complete and was by the board of the Longitude Act considered worthy of a trial. In 1736 Harrison sailed from Spithead to Lisbon and back, calculating the point of landfall upon his return correctly. (07) The Board, pleased, granted Harrison funds to develop the timepiece. After three years version two was ready, which was followed a whole 17 years later by version three. Both functioned well, but neither was perfect. Harrison then took a different route and developed the fourth version as a watch, 13 cm in diameter, much smaller than the larger clocks he had produced so far. On its first voyage from England in 1761, it was only five seconds slow when it reached Jamaica, but this was, to the Board, pure luck. Harrison contested, thinking it was within the acceptable limits. However, he could only get a re-trial, this time being off by 39 seconds. The Board attributed this to luck again, mainly – it is believed – because the Board was composed of a majority of astronomers who all favoured a measurement using Lunar Distances, similar to what Newton had prescribed. Harrison, however, moved on to his final timepiece, completing his fifth after another three years. This time, though, rather than submitting it to the Board, he obtained an audience with King George III and persuaded the King to put the piece to the test himself. The King kept the watch in the palace and had it observed daily for ten weeks, finding that it was accurate to within one third of a second per day. Harrison was finally awarded about 8,000 pounds, but was never given the official prize by the Board. Nevertheless, his final clock became the template from which to develop and perfect the discovery of the longitude as the final feat in the development of time. Now, the radix of time can of course be discussed endlessly and much more accurate devices are available today, but every clock we consult ticks with a particular rhythm, and it seems that the beat stems from the ingenious inventions of John Harrison. Each tick of time is an echo of his making.

It is not surprising that just a few years after the longitude became somewhat controllable, and as time and place became more defined, that a movement emerged to conclusively determine certain aspects of measurement. The concept of the Metric System had been developed already in the sixteenth and seventeenth century by the French mathematician and military engineer Simon Stevin, in a small pamphlet called De Thiende and later by, among others, John Wilkins in An Essay Towards a Real Character and a Philosophical Language in 1688. Nevertheless, the Metric System wasn’t practically implemented until the French Revolution. The development of the concept came about for many reasons, but one stands out in particular. There were, only in France, an estimated quarter of a million different manners in which things like lengths and weights were measured as the Revolution set in. The need for a ubiquitous system, as trade travelled far and wide, is apparent. And as the French nobility surrendered their rights to control weights and measures only three weeks into the Revolution, the field was open for a new unifying system, as it was said ‘for all people, for all time’. Those responsible, L’Assemblée nationale constituante (The National Constituent Assembly), were faced with three possible references: the length of a simple pendulum beating at a rate of one second at a latitude of 45°, the length of one quarter of the equator or, the distance from the North pole to the equator, a quarter meridian. Since the pendulum beating at a rate of one second involved time and varied at different points on the globe the quarter meridian seemed to be the simplest solution to calculate from, and the most universal. Introduced on 26 March 1791, the metre was defined as being equal to the ten millionth part of one quarter of the terrestrial meridian.

The attempted, and for a while successful, effectuation of decimal time two years following the metric systems implementation might have just been a French thing, but what it shows is the somewhat arbitrary way time is counted. To alter it would perhaps not be that difficult, aside from getting everyone on board. And indeed, as some have argued and still argue, decimal time would make certain things a bit easier. Long before the period of French radical reformation a great deal of prominent reasons were put forward. Most frequently quoted is Jean le Rond d’Alembert, the mathematician, mechanic, physicist, philosopher, music theorist and editor, who wrote an entry in Encyclopédie 1754 saying:

It would be very desirable that all divisions, for example of the livre, the sou, the toise, the day, the hour, etc. would be from tens into tens. This division would result in much easier and more convenient calculations and would be very preferable to the arbitrary division of the livre into twenty sous, of the sou into twelve deniers, of the day into twenty-four hours, the hour into sixty minutes, etc. (08)

But at that time it was church bells that set the rhythm, and the ecclesial community was, as  it tends to, reluctant to chance anything. It wasn’t until the Revolution that the attempt was made, and for seventeen months d’Alembert’s calculations were a bit more convenient until time slipped back into its usual sway. What is argued today by the few who still insist as grounds for a ten-based system of time is of course the decimals ubiquitous presence in nearly everything else, alongside the physical feature of ten fingers to count on. This argument though, sets aside that in several places counting on fingers is conducted by using one hand only, with the thumb pointing to each finer bone on the four fingers in turn, to twelve. The arguments also ignores that historically a better part of the methods of measuring used other numbers than ten as their basis: duodecimal (base–12), hexadecimal (base–16), vigesimal (base–20), and sexagesimal (base–60). As much as it would perhaps be theoretically possible to change time keeping, it might not be as casual as d’Alembert and his followers would have it.

Coming back from this drawn-out, yet abbreviated history lesson, what have we gathered? And, more importantly, what then does it have to do with the piece Historical Time? For one, it is all embodied in Johannessen’s clock. The work cries neither for change nor for preservation, it doesn’t set itself within a discussion of problems or advantages, it proposes no solution or argument and doesn’t wish for standardisation à la French Revolutionists. Rather, and quite beautifully, it simply runs differently and by this carries all manners of measuring time on its shoulders. Because when we speak about time – the kind a clock or watch shows – the origin of that particular time must be taken into account and thus, through Johannessen’s clock, we turn to history to figure out why and how, exactly, it runs differently. With the metre, the centimetre and kilogram in place, French Revolutionary Time was one of the most recent attempts to rethink the measuring of time. It worked for a short while, but, as we know, never settled in. Possibly because of the sexagesimal stronghold and the history that comes with it. Maybe time was just too established to change, no matter how much easier it would be to compute with other aspects of science. The work Historical Time, of course, isn’t necessarily about horology, but without a doubt contains it all. When a clock runs differently from the norm, what time it actually is comes to matter more. And when the clock running differently in turn runs according to one of the few serious attempts in history to in fact run things differently, it comes to bear a particular significance. Looking at Johannessen’s clock, again, with the history of horology in mind, it is astonishing what a clock can tell besides time.

 

(01) Richard A. Carrigan Jr., ‘Decimal Time’, American Scientist, Vol. 66, No. 3, May– June 1978, pp. 305–13.

(02) Otto Neugebauer, ‘Studies in Ancient Astronomy. VIII. The Water Clock in Babylonian Astronomy’, Isis, Vol. 37, No. 1/2, May 1947, pp. 39–40.

(03) Vitruvius, Ten Books on Architecture. Translation by Morris Hicky Morgan, 1914, p. 271.

(04) J. Lennart Berggren and Alexander Jones, Ptolemy’s Geography: An Annotated Translation of the Theoretical Chapters, 2001.

(05) Dava Sobel, Longitude: The true story of a lone genius who solved the greatest scientific problem of his time, 1995, pp. 4–5.

(06) Sobel, op. cit., p. 60.

(07) Sobel, op. cit., p. 79.

(08) Hector Vera, ‘Decimal Time: Misadventures of a Revolutionary Idea, 1793–2008’, KronoScope, Vol. 9, No. 1, 2009, pp. 29–48.