Hourglass what color is the sand. Hourglass
INTRODUCTION
The history of watches goes back many centuries. And at different times they were both a piece of furniture and an ornament, showing the prestige of the owner of an intricate clock or a massive mantel clock, or a floor-wall clock. And as for the forms of watches, here the fantasy of watchmakers is simply limitless. What masters and customers did not come up with to surprise the world! It is simply impossible to describe all the splendor of watches, which are sometimes a real work of art. Today, watches are a sign of prestige, which has a symbolic meaning, a sign of dignity, style. Clocks have long ceased to be a mere instrument limited to its main function, they not only indicate the time - they stand up for the right to aesthetic appeal and personal respect.
HOURGLASS
The principle of the hourglass was known in Asia much earlier than the beginning of our chronology. One of the oldest references to such a clock is a report from 1339, discovered in Paris, containing instructions for preparing fine sand from sifted powder of black marble, boiled in wine and dried in the sun. Although the hourglass was a late arrival in Europe, it quickly spread. This was facilitated by their simplicity, reliability, low price and last but not least, the ability to measure time with their help at any time of the day or night. The disadvantage that prevented the wide use of these watches was the relatively short time interval that could be measured without turning the watch over. Typically, an hourglass was calculated to work for half an hour or an hour. Less common were hourglasses designed to continuously measure time for 3 hours, and only in very rare cases were huge hourglasses built, designed for 12 hours. The combination of several hourglasses into one did not give a decisive improvement. For example, a set of four hourglasses in a single case was arranged in such a way that the contents of the first flask spilled out in a quarter of an hour, the second in half an hour, and so on. The accuracy of the hourglass depended on the manufacturing technology of the sand itself. The flasks were filled with annealed fine-grained sand, sieved many times through fine sieves and thoroughly dried. The sand thus treated had a reddish color; light whitish sands came from fried finely ground eggshells; grayish sand was made from zinc and lead dust. Hourglasses were necessary on ships, they were called "ship bottles". Now the hourglass is widely used in medicine.
"... And in eternity the hourglass will remain like a child's toy."
In the distant past, an old hourglass that served in Ancient Greece the symbol of the god Kronos, the chief judge and the keeper of time, was made from two glass flasks, which were connected to each other through a diaphragm made of metal, glass, mica or wood. With prolonged use of the hourglass, these diaphragms were often erased, increasing in diameter. Sand poured faster, and the "course" of time was broken.
Since 1750, glassblowers have learned to make a single glass flask for hourglasses. The flask smoothly passed into a narrow neck and expanded again. They began to fill it with sand through a small hole in the bottom, which was then covered with wax. Since 1800, masters have learned to seal the hole in the flask.
Sand has always been the main filler for hourglasses. The accuracy of the hourglass depends on the condition of the sand, the shape of the flask and the quality of its surface. The sand must be dry, homogeneous, round grains of sand should preferably have the same size and high resistance to abrasion. In the Middle Ages, they also used marble, zinc or lead dust, as well as ground eggshells. Since the 13th century, various recipes for making “sand” for clocks have been known. It was sieved, washed, boiled and annealed. Nowadays, instead of sand, tiny glass balls are used.
The hourglass was once the main, fairly accurate instrument for measuring time. Since the 15th century, they have also been used on ships for navigation. During world travel Magellan installed 18 hourglasses on each of his ships. Specially assigned sailors turned the hourglass over.
How does the classic hourglass work?
At the top of the flask, the sand rushes down and falls under the action of gravity. At the beginning of the movement, the growing flow of falling sand grains is opposed by the reverse flow of air displaced from the bottom of the flask, which rushes upward, trying to pass between the individual grains of sand.
The speed of the sand jet is determined by the speed of the falling grains of sand when an equilibrium occurs between the force of gravity acting on the grains of sand and the air resistance force that occurs when the grains of sand fall.
The steady stream of falling sand gradually leads to an increase in air pressure in the bottom of the flask. When the stream of grains of sand is almost dry, you can see how the stream of air, escaping from the bottom up, picks up the last grains of sand in the upper part of the flask and lifts them a few millimeters before they finally fall down.
Why can you measure time with an hourglass?
Sand is a complex material that sometimes behaves like solid and sometimes as a liquid. It seems that in an hourglass a uniform stream of sand is similar to the flow of liquid, but there is an essential difference. If it were a liquid, then its amount flowing through the hole of the clock would depend on the height of the liquid column above the hole. And the amount of sand passing through the hole in the hourglass per unit of time does not depend on the height of the sand above the hole. That is why sand can be used to measure time in an hourglass.
The constant speed of the sand flow is due to the redistribution of forces arising in the thickness of the sand, which appear at the points of contact of the grains of sand. In large volumes of sand, due to these points of contact, "networks" of grains of sand are formed, in which domed "bridges" appear.
These bridges create pressure on the glass walls of the flask. The underlying layers of sand are to some extent released from the pressure of the upper layers. As a result, the average sand pressure over the hole, even with varying sand levels, remains almost constant. This results in a constant velocity of the sand jet in the hourglass.
How can you "manage" time?
Let's hang the hourglass on an elastic thread (elastic band) and make it oscillate up and down. if they were, for example, standing on a table.
The diameter of the hole connecting the halves of the flask is usually made as small as possible in order to increase the sand pouring time with a smaller amount of sand in the clock, i.e. increase the time of the hourglass.
The flow of granular matter (sand) is different from the flow of a liquid. Sand flows from beginning to end through the hole at the same speed. This property is based on the occurrence of vaults (bridges) inside the sand. In an hourglass, this can even cause the hole to close up and stop the sand from flowing down. When the clock moves with acceleration up or down (for example, when swinging), such overlapping bridges fall apart.
How else can you "influence" the time?
For example, grasp the bottom of the flask with your palms. After some time, "time will stop", the flow of grains of sand will stop. What seems here to be a mystical laying on of hands can be explained quite logically. When the bottom of the flask is heated, the air in it heats up, expands and tends to rise to the top of the flask, and then the uniform flow of grains of sand in the hourglass can be disturbed or even completely stopped.
Interesting phenomena can be observed in some unusual hourglasses!
For dry sand, the angle of repose of a pile of sand formed at the bottom of the flask is about 30-35 degrees. This value also depends on the shape of the grains. Angular sand grains create steeper slopes, while rounded grains create gentler slopes.
If you fill an hourglass with sand with grains of sand of different diameters, then when a jet of sand is formed, the grains of sand will begin to be distributed in a very interesting way, both in the upper part of the flask and in the lower one.
At the bottom, a small cone first forms, the sand flowing from above forms sand avalanches that slide down the slope of the sand cone. In this case, grains of sand are sorted by size: large ones accumulate mainly at the foot of the cone, and on the slopes of the cone, sand lies in separate layers of the smallest grains of sand and larger grains of sand.
This "banding" is explained in two ways: the smallest grains of sand can penetrate between the large ones and form a layer, while the large ones can more easily roll down the slope, and thus they also create their own layer.
These processes are constantly repeated.
And something similar happens in the upper part of the flask, only here, when the sand moves, a conical funnel is formed.
This hourglass model is similar to the regular hourglass, but it has two differences. First, the sand is between two flat plates, and second, the clock will be filled with sand containing grains of sand of different sizes. Hence the appearance of the above-described "striped" effects.
On the example of such a scientific "toy" serious people study serious problems that arise, for example, when storing bulk materials.
Along with the classical ones, there are also modern hourglass designs, the work of which would be interesting to consider. Such clocks are even called "paradox clocks".
You won't believe your eyes, in this watch "sand" flows from bottom to top, however, the laws of nature remain in force!
A glass container is filled with a liquid of high density and small balls with a density much less than the density of the liquid. In a denser liquid, balls with a lower density rise, as expected, up. This is the basic principle of the paradox clock, on the basis of which the "sand" rises from the bottom up. And everything repeats in a new way with each turning of the clock.
Unusual hourglasses may have tiny plastic balls or air-filled glass balls as "sand". Hollow transparent balls, partially filled with tinted water, also look very nice.In the vertical position of the clock, a relatively dense and not very uniform flow of balls upwards occurs. The balls must penetrate upward through a narrow hole, and due to the viscosity of the liquid, they partially entrain it along with them, while the liquid also tends downward.
Basically, the rate of lowering and rising of a ball in a liquid depends on the difference in densities of the balls and the liquid, on the diameter of the balls and on the strength of the liquid, and the strength of the liquid is highly dependent on temperature.
If you start the paradox clock, and let at least a few balls rise up, and then put the clock on its side, then you can clearly see the individual balls slowly rising up.
In this case, you can even have time to determine the rate of rise of individual balls.
If you put the clock again vertically so that the balls begin to rise in a stream to the upper part of the flask, then in the lower part of the flask, almost completely filled with balls, you can clearly see the "hole" shifting down. This phenomenon can be compared to the movement of a “hole” in a semiconductor.
"Forgetful" or "naughty" hourglass.
An ordinary hourglass is lowered into a cylinder filled with water. The outer diameter of the hourglass is a few millimeters smaller than the inner diameter of the cylinder. At rest, the clock, like a float, is at the top of the cylinder, and all the sand is at the bottom of the flask.
If the cylinder is now inverted, then at first the hourglass remains at the bottom of the cylinder, although the sand has already begun its movement. And only when almost half of the sand has flowed, the hourglass rises to the top of the cylinder. And already at the top of the cylinder, the rest of the sand in the clock is poured into the lower part of the flask.
The "forgetful" hourglass will begin to float only some time after the cylinder is turned over.
Why doesn't the hourglass rise immediately after the cylinder is turned over?
The hourglass inside the cylinder has an average density less than that of water. So the clock goes up. If you turn the watch over, then at first almost all the sand will be in the upper half of the flask, the center of gravity of the watch will be, respectively, above the middle of the watch.
If the clock were not in a narrow cylinder, but in free water, then it would immediately turn over due to the resulting torque. In a narrow cylinder, they are pushed against the inner wall of the cylinder. Here sticking (static friction) occurs, which prevents the watch from rising quickly.
Only when almost half of the sand has flowed out will the watch's center of gravity drop below the middle. The static friction against the cylinder wall and the torque will disappear, now the watch can float to the top of the cylinder.
"Floating Hourglass"
The next example of an unusual hourglass is a variant called "Floating Hourglass". Here, a cylindrical hourglass is in a cylinder filled with water.
The outer diameter of the hourglass is only slightly smaller than the inner diameter of the cylinder. Due to the viscosity of the liquid, the hourglass will rise and fall very slowly in such a cylinder.
According to its principle of operation, an hourglass located in a narrow cylinder is similar to a device for measuring the viscosity of a liquid.
The time during which the sand is poured through the neck into another vessel is usually from a few seconds to several hours. Previously, to increase the interval of measured time, even sets of hourglasses were compiled in one case.
Hourglass "Wheel of time"
In our time, they have learned how to make an hourglass with a "plant" for the whole year In the capital of Hungary, Budapest, every year on the last day of December, a giant hourglass "Wheel of Time" several meters high makes a half-turn to start a new annual cycle of work.
The flip of the hourglass is always done in one direction, the old fashioned way: with the help of cables and a simple mechanism.
And here is the focus!
Did you know that you can set the egg on the table with the pointed end down?
Inside such an egg, an asymmetrical hourglass is made. When all the sand is in the part of the flask that is symmetrical with respect to the egg, then it can be placed on the table at the sharp end and it will stand
After a while, when the sand begins to fall off, the center of gravity of the egg will shift, and the egg will fall. The second time it will not be possible to put it on the sharp end until all the sand in the watch is poured back into its original position.
In our time, the hourglass has acquired many different variations of execution and has already moved into the category of souvenirs and scientific toys.
Instead of sand and air in an hourglass, for example, balls and a liquid or two liquids that differ greatly in density can be used.
Or maybe you will be able to invent your own version of the "hourglass"?
Hourglass in the Middle Ages
It was the Middle Ages that made the big jumps in the development of the history of the hourglass.. One of the oldest references to clocks dates back to the 14th century and contains advice on preparing special, fine sand for use in hourglasses.
Hourglass appeared in Europe rather late, but despite this, they quickly entered the everyday life of almost every person, this was facilitated by low price, ease of use, reliability, and most importantly, the ability to measure time regardless of the time of day, this favorably distinguished them from sundials.
The most common watches had one significant drawback - this is a relatively small interval, an hour or half an hour. A rarity was a watch that could measure 3 hours, and quite a few were designed for the relatively long time of the hourglass. These were huge, bulky structures that could count 12-hour intervals.
Hourglass production
The most important thing for the accuracy of the hourglass was the quality of the sand., it must be sieved through numerous sieves, thoroughly dried and annealed. Glass flasks for making watches were already produced according to well-known technology. A plate was inserted into the place where the flasks were joined, which was supposed to regulate the rate of pouring. To fasten two flasks, the place of their junction was tightly wrapped with thread and additionally covered with resin.
For accuracy, the shape of the flasks and the quality of their surface also mattered. With a very long operation of the hourglass, their accuracy deteriorated. This was due to the fact that the inside of the flask was gradually scratched by sand, and the fact that the sand was crushed into smaller fractions also played a big role.
Hourglass - photo
We present you a photo of various forms of hourglasses.
Hourglass Meaning
The hourglass is a symbol that reminds us of moderation., that time is fleeting, and it is not necessary that the allotted time be reduced by excesses. Two vessels represent cyclicality, the change of life and death, chaos and order.
Certainly, getting away from the classic hourglass shape is far from possible, because two interconnected flasks and a frame are the basis of such watches. But you can change the very shape of the flasks and the frame supporting them to whatever you like. For example, an excellent gift in business circles is an hourglass whose flasks are the company logo. There is also the opportunity to experiment with materials: colored glass, stones of various breeds, wood, metals (perhaps even precious) can make an hourglass unique in its kind.
The world's largest hourglass is 11.9 meters high., and their cycle is 1 year, this is the greatest device for measuring time. This clock in July 2008 could be seen in Moscow, on Red Square. The smallest watch, only 2.5 cm high, was created in Germany, in Hamburg, the sand from the top flask of this watch spills out in just 5 seconds.
Even considering that the hourglass has flaws and is not the most accurate, they were used even after the invention mechanical watch, in the 20th century they were used in telephone exchanges and in courtrooms.
Currently, the hourglass plays a more decorative role., as interior design elements. This ancient invention is also used during some medical procedures.
People have been measuring time for a very long time. For this, water and sunlight, later the energy of grains of sand, the mechanical force of springs, and today most often the vibrations of piezocrystals.
Once upon a time, one of the main devices for measuring time was an hourglass. It is authentically known that the principle of their construction was known in Asia much earlier before the beginning of our chronology. However, in the ancient world, despite references to bottle clocks and attempts to make glass, the hourglass was not constructed. In Europe, they appeared in the Middle Ages.
It is documented that in the 14th century, sand from marble, lead or zinc dust, quartz, and also from eggshells was used for the production of hourglasses. The smoother the glass, the more accurate the movement. It also depended on the sand itself and on the shape of the vessels. The presence of a diaphragm made it possible to regulate the amount and, accordingly, the rate of pouring of grains of sand. True, in those days, the craftsmen did not manage to achieve the accuracy and durability of the hourglass due to the mechanical destruction of the grains.
The time interval for which the clock is calculated usually ranged from a couple of seconds to one hour, less often several hours. However, there are exceptions, which are located in Budapest (Hungary) and Nimes (Japan). These hourglasses reach a height of several meters, and their cycle is one year.
For a long time, ships used 30-second hourglasses, which were used to measure speed and half-hour watches. Thirty-minute chronometers were also used in court hearings, and thirty-second ones were used in medicine.
In the history of hourglasses, there are many attempts to improve them, for example, using spring mechanisms to turn over, or replacing grains of sand with mercury. But all these innovations did not take root, and modern watches are the same as several centuries ago.
Today, few people use an hourglass to measure time, but a lot of people face it as a symbol. So with users of the Microsoft Windows operating system, this happens with every session, just the mouse pointer turns into an overturning hourglass, showing the system is busy.
Hourglasses are one of the oldest types of devices invented by people to measure time.
Despite the active development of watchmaking and the emergence of more advanced mechanisms, hourglasses are still used today.
Start
The history of the emergence of the hourglass lacks specifics and reliably confirmed facts, however, based on the surviving sources, it can be assumed that the principle of constructing such a device was known in Asia even before the birth of Christ. Despite the fact that the bottle clock was mentioned by Archimedes, and in Ancient Rome the first attempts to invent glass were made, in the days of Antiquity no one was able (or maybe did not want to try) to make an hourglass.
Middle Ages
The next milestone in the history of the hourglass was the Middle Ages. At that time, the craftsmen who worked on improving the water and solar grandfather clocks also took up bottle designs. Due to their low cost and ease of use, they immediately gained incredible popularity.
One of the first European hourglass models was made in Paris. The record of this was dated 1339, and the text of the message contained instructions on the preparation of fine sand (for this, the powder of black marble, previously boiled in wine and dried in the sun, was sifted). The quality of the sand was one of the fundamental factors on which the accuracy of the clock depended: in addition to marble, greyish sand made from zinc and lead dust, reddish fine-grained sifted sand, and light white sands made from roasted ground eggshells were used. The granularity and flowability of the sand must necessarily be uniform.
Most often, sand was covered with the expectation that the clock would run for thirty minutes or an hour, but there were also models that worked for three and even twelve hours.
For the manufacture of body elements of sand, mantel and wall clocks with a strike, the development of transparent glass production technology was used. For bottle watches, it was converted into spherical flasks.
For maximum accuracy, the glass had to be smooth, without defects. In the place where the neck of the vessel narrowed, a horizontal metal diaphragm was placed, the opening of which served to regulate the amount and speed of pouring grains of sand. At the junction, the structure was tied with a thick thread and fixed with resin. Unfortunately, medieval craftsmen never managed to make an hourglass that would not be inferior in accuracy to a solar one: with prolonged use, the grains of sand gradually became crushed, and the hole in the diaphragm expanded, thereby accelerating the passage of sand.
new time
With the advent of interior, as well as women's and men's wristwatches with a mechanical movement, the hourglass had to be improved so that they could compete with more accurate time measuring devices. To do this, in the cities of Augsburg and Nuremberg, the production of hourglasses began, the design of which consisted of four systems of flasks in one case. At the same time, the mathematician De la Hire created an hourglass capable of measuring second intervals. Attempts to replace sand with mercury were made by the astronomer Tycho Brahe. However, the last two innovations were not as significant as Stefan Farfleur's invention of the spring mechanism, which provided automatic tilting of the watch.
XX century and modernity
Despite the fact that the hourglass is not the most accurate and has some drawbacks, they did not cease to be used in the twentieth century. An hourglass with an automatic tipping mechanism was used in the courtroom, as well as at telephone exchanges (to control the time of short telephone conversations).
On present stage antique hourglasses can serve as a decorative element, and diamond-encrusted models are especially popular among collectors. And, finally, the bottle-shaped electronic watch, on the screen of which not grains of sand, but pixels are poured, reminds us of the history of the development of watches.