Things that Yoram knows: why are there 24 hours in a day and who decided what time it is?

 The day is divided into two dozen hours because the hour was born even before the decimal system defeated the competing base 12. The fixed hour is a relatively new invention

Nitzan asks 2 questions about time units. Why is the day divided into 24 hours? Who decided what time it would be?

Let's start with the first question, why exactly 24? The day is divided into two dozen hours because the hour was born before that the decimal system defeated the competing base 12 system.

The division of the day into 12 hours originated in Babylon, migrated to Greece and from there made its way to Rome and Europe and completed its victory in 1628 when it was adopted in Imperial China where it replaced the decimal time system in which the day is divided into 100 units. The French Revolution aspired to establish a rational world in which all measurements would be decimal and indeed in the 90s of the 18th century the last (and probably the only) attempt to create a decimal time system was made: the day is divided into 10 hours, each such "hour" into 100 minutes and each minute into 100 seconds. Despite the obvious advantage of this method in which every hour of the day can be written as a decimal fraction, France abandoned the revolutionary clock along with its friend The ten-day week.

 The division into dozens is ancient, but our time is completely different from that of our ancestors. The time of the ancients was 1/12 of the time between sunrise and sunset, a "natural" division that is convenient to measure with a sundial. This clock which is nothing more than a pole fixed in the ground is easy to build and requires no maintenance. The shadow is a convenient means of telling the time even without a sundial, in Aristophanes' comedy a wife orders her husband to return to dinner when his shadow lengthens to 10 feet. In "The Canterbury Tales" from the 14th century, Geoffrey Chaucer describes a pilgrim who uses the shadows of trees to calculate the time

"Nevertheless see: the shadow of every upright tree

They were exactly as long as the body

 the cast Calculated as Dilkman:

If it's the length of the shadows, that is

The sun shines and rises

He climbed to a height of 45 degrees (XNUMX⁰).

And the time at the latitude here

According to all this she is ten of course" ("The Attorney's Story", translated by Shimon Zandbank)

In some places the sundial was the popular way of telling the time until very close to our time. Post, a British officer sent to mark the border between Peru, Bolivia and Brazil at the beginning of the 20th century built a sundial in Riberalta, a town deep in the Amazon basin. The clock was inaugurated in a solemn ceremony at noon, but at night a riot broke out when residents tried to set the time by candlelight, after heated debates that escalated into loud calls condemning British imperialism, a policeman appeared and scolded the crowd, "Fools, don't you know that you have to wait for the moon to rise before you can read the time?" 

Indeed, the sundial leaves the night without a division of time, so while the division of the day into 12 is very ancient, the division of the entire day into 24 is much younger. The night was content with a rough division into 3 "repositories". The line "Ashmorat Tikhuna is kissing for the third" in Naomi Shemer's poem "The celebration is over" is spread around 2 am. Apparently, our ancestors had at their disposal a means of dividing time into equal hours: the water clock. From a jug that was kept full, the water flowed at a uniform rate into a smaller vessel that stood on a scale so that after an hour the weight of the vessel was on the weight in front of it. A water clock was used when an exact division of time was required: this is how the times allocated to the plaintiff and the defendant in the court were allocated and this is how the irrigation time quotas for the fields were determined.

The water clocks became more sophisticated over the years, instead of the weights a float was installed that rose with the rise of the water level and activated various mechanical devices. A particularly sophisticated water clock operated in the sixth century in the market square of Gaza: the mechanism included bells ringing to mark the time, doors that each opened at "its" time and revealed one of the 12 signs of the zodiac, and plenty of mythological figures that moved as the water vessels filled.

But surprisingly, for hundreds of years, the water and sand clocks did not lead to a uniform distribution of time: in order to preserve the connection between the hour and the movement of the sun, the balancing weights were changed so that the hour would continue to be long in the summer and short in the winter. This difference between our time and the time of our ancestors is not technical but expresses a different perception of time. The ancient clocks saw the hour as a natural unit of time determined by the movement of the sun and the stars in the sky and not as an arbitrary means of determining schedules. The slogan "time is money" coined by Franklin at the dawn of modernity sounds like a cliché to us, but it marks a philosophical revolution: time has become a means of production. For comparison, in the Middle Ages the Catholic Church justified the prohibition of usury by saying that a mortal must not use the time that is God's property for his own personal gain.  

The very idea that every moment has a special number for it and that the answer to the question "What time is it?" Unequivocal, available and free, new and revolutionary.

Most humans throughout history have gotten along just fine without ever knowing what time it is. The daily routine was conducted according to the natural cycles of the movement of the sun across the sky, the change of the wind, the tides or the activity of the animals. This is how Jacob our father, without a clock, recognizes the violation of the order of the day among the shepherds he meets in Haran "There is still a great day, not the time of the offering." The shepherds knew the "gathering time", the sailors the times of high tide and most of the people, who lived in the villages, got up at sunrise, rested during the heat hours and finished their work at sunset. An agreed division of the day was necessary only for a thin layer of the city dwellers: people who were required for commercial or legal meetings and for whom sundials and bell ringers of religious institutions were intended.  

The modern hour: the 24th part of a day whose length is the same everywhere and throughout the year was created in the Middle Ages in the monasteries of the Benedictine order who sought to guide themselves to humility and obedience to God. In this framework, private property and personal control over time were denied. The strict schedule included wake-up times, work, meals and, of course, prayer. From verse 7 in the psalm of the 70th Psalm, "Seven on the day of your glorification.." the bandits learned that they must establish 50 times of prayer each day and verse 12 in the same chapter, "Midnight and okum to give thanks to you.." requires, according to their method, an accurate measurement of the night. This religious need created a motivation to perfect mechanical watches. There are those who reverse the creation and claim that the monks became enslaved to a meticulous daily routine because they had clocks at their disposal. There were also secular motives for setting a uniform time. In the southern countries of the clock's origin, the difference between summer time and winter time was small, about 13 minutes for the long hour and 14 minutes for the short day. In Scotland, for example, a summer hour was about three times longer than its winter sister, this is in addition to the rarity of sunny and shady days on which the sundials can be used. Somewhere at the end of the 1th or the beginning of the 12th century, a technological breakthrough was achieved - the escapement, a toothed wheel with a metal tab, makes its movement one-way and enables the "counting" of steps from a constant rotary movement. These first clocks did not include a dial display and were content with operating a bell. Most of the public didn't know how to read a clock face anyway and all that was required was counting from XNUMX to XNUMX rings. From the churches the clock moved to the cities, people were used to the bells that announced various events - prayers, opening and closing of the city gates, the beginning of the market day, etc., as the cities grew, the events that had to be announced also multiplied. The city of Milan of the Renaissance is described as an acoustic chaos of ringing that announced countless commercial, religious and legal events. The central clock with its regular chimes provided a uniform public time and also organized the time of darkness with the same level of precision as the daytime hours.

This is how urban Europe got used to a day of 24 equal hours while the majority of the rural population simply managed without clocks at all. But even in the city centers the connection to the natural clock of the sun's movement still remains: 12 noon indeed marked half the time between sunrise and sunset and on the equinox the sun rose at 6:00 and set at 18:00. Since the sunset and sunrise times vary in the east-west direction, each city had its own clock and a local astronomer would adjust it. Between the east of England and the west, for example, there was a time difference of about half an hour. When an accurate portable clock was invented for maritime navigation purposes, the Greenwich Observatory began to "sell time" to the clocks of nearby London, that is, to allow them, for a fee, to set their clocks according to it. The need for a uniform clock for different cities arose only when the railway system spread in the middle of the 19th century and a single time was required for stations on the same line. Naturally, the time of the main city on the track was chosen for this purpose. In England, most of the railway lines reached London and thus the Greenwich Clock became the time of England and later the clock tower of all humanity. The clock lost the last connection to nature and the process was completed: time became artificial and dictated from above. The change in the perception of time is the great stamp of the industrial revolution on humanity. To an observer from a "watch culture" life before him seems relaxed and extravagant. The work is carried out in bouts of multiple activity accompanied by idle periods. A central characteristic of such a life is the non-separation between work and life and between friends and co-workers.

Once the mechanical production machines were invented, the work became organized and coordinated, again it was not possible to rely on the leisurely movement of the sun on the dome of the sky. The clock, which until then was a luxury accessory or a device to serve the church bell, became a tool for work and control. At the dawn of the industrial revolution, conflicts are documented between workers rebelling against the incomprehensible tyranny of the hands. The lack of trust deepened because the clock was owned and cared for by the owner of the house and out of reach of the laborer. The political and religious establishment welcomed the development. Idleness leads to unburdening and the discipline provided by the clock keeps danger away. Workers in industries where the industrial revolution was late to reach and who still worked as freelancers without a clock were considered lazy and morally promiscuous. An agenda dictated by a mechanical clock is considered a clear sign of progress and innovation. In the South of the USA during the period of slavery, there was no economic need for the new methods of organizing time (there is no need for a time clock for those physically bound to the workplace) and yet many plantation owners adapted to the innovative agenda. The watch was a sign of modernity and progress that could be imported without an excess of problematic modern ideas from the conscience.

After the clock entered the workplace, school was the next natural destination. There a fixed hours system was enthusiastically adopted which is supposed to impart discipline and work habits copied from the factories. Thus, between regular bell rings, we were all educated until it is difficult for us to even imagine a world without schedules.

Did an interesting, intriguing, strange, delusional or funny question occur to you? sent to ysorek@gmail.com

More of the topic in Hayadan:

• John Harrison, the watchmaker who brought about the accurate measurement of longitude, a task that astronomers had failed at
• what's the time? Depends on who you ask
• The designers of the observation instruments of the 21st century win the Dan David Prize in the future time dimension, dedicated this year to astronomy
• Really cool