Sundial. Watch History

The largest sundial in Abano Terme in Europe. Places worth visiting for all visitors.

Who would have thought that such a small town has the largest sundial in Europe? And yet, leaving the church of San Lorenzo, on the left side we can see "Piazza del sole e della pace" - the square of the sun and the world on which the Abano clock is placed!

Sundial Abano. Creators

The sundial was designed by the astronomer Salvador Conda, the designer and architect Giuliano Genta, Giovanni Paltinieri, who had the art of representing the celestial spheres and the movements of the stars relative to the observer, and the impresario Miro Mazzuccato.

Explanation and meaning

All this joint work was laid out at the end of 1996 horizontally on an area of ​​3000 sq.m. polychrome marble. Through its multiple elements, it indicates the philosophical and astronomical path. Starring the sun, sky, stars and the flow of human life. They are placed in space and time, and this indicates our limit regarding the mystery of the universe. The four elements that make up the universe, water, air, fire and earth, are engraved in marble, connected by a geometric play of lines and circles that lead to drought, moisture, heat and cold. The wind rose then with its notch, through the equation, looking at the position of the sun, allows you to calculate the local time. The central block of marble "gnomon" is the clock indicator. On its sides are Pietro D'Abano and Galileo Galilei, both connected with the history of the spa town. Galileo, for example, lived in Padova, but very often came to Abano to buy meat from a butcher who had a shop across the street from the square.

Afterword

The sundial stands out for its high scientific, astronomical and educational value. To visit Abano Terme and not go to see them is unforgivable! The area is beautiful, clean, well-groomed, equipped with typical Italian houses. Nothing special, but impressive. It is especially pleasant to walk on a summer evening and dedicate yourself in peace to the square and the church of San Lorenzo. Unfortunately, in recent times, fewer and fewer people attach importance to such places, but they have so much mystery that you want to unravel. They say that in the square of the sun and the world, you can acquire the harmony of the body and spirit ... although in Abano everything contributes to this!

IIntroduction

IIAbout the sundial

1. Sundial in Moscow
2. sundial device
3. Types of sundial

a) Horizontal sundial

b) Vertical sundial

c) Equatorial sundial

d) Analemmatic sundial

1. The history of the sundial

a) Sundial in ancient China

b) Sundial in Ancient Rome and Ancient Greece

c) Sundial in Ancient Russia

d) Sundial in the UK

III Sundial in the school yard

1. My double dial sundial
2. Sundial manufacturing steps

I V Conclusion

V Sources of information

I Introduction

Last year I read in the newspaper “Moscow. Centre." dated November 6, 2015 No. 37 article about Ekaterina Shamina's sundial. It turned out that in Moscow there are 8 sundials. I got interested in this topic. I wanted to look at this sundial, study its history of creation, find out where they are, how they are used. A sundial is a very handy tool for telling the time on a sunny day. If a sundial is made in the school yard, they can be used as a teaching aid both in elementary school in the lessons of the world around, and in high school in the lessons of geography and physics. They allow the movement of the shadow to clearly trace the daily and annual movement of our planet. In this way, purpose my job is to create a sundial in our school yard.

Criteria by which you can evaluate the result of the work:

• a) a sundial in sunny weather should tell us the time;
• b) a sundial should be simple and easy to use;
• c) a sundial should contribute to the formation of the scientific worldview of schoolchildren;
• d) the sundial should look aesthetically pleasing and serve as a decorative element of our school yard.

I organize my work according to the following plan:

1. Walk around Moscow and search for the sundial of our city.
2. Collection and analysis of information on the history, device, types, principle of operation of sundial.
3. Making a sundial in the yard of our school.
4. Checking the effectiveness of the created tool.

II.About the sundial

• Sundial in Moscow

On the weekend I traveled around Moscow and saw with my own eyes all these sundial, which was mentioned in the newspaper. I wanted to see how organically they fit into the architectural appearance of our city.

1. The oldest sundial that has come down to us is installed on the Lopukhinsky Chambers of the Novodevichy Convent. They presumably belong to the 17th century.

2. From the clock on the Church of the Resurrection of Christ in Kadashi, written on the facade of the temple, which was built in 1687-1713, only some symbols have been preserved.

3. Also in Moscow there are "missing" sundial - on the so-called "Bruce's house" (now d. 2 on Spartakovskaya street). All that remained of them was a stone board - a trapezoid. There is a legend that it blushes before wars and revolutions.

4. Also, a sundial has been preserved on the building of the main building of the old Moscow University, located at st. Moss; d. 11.

5. The clock on the building of the former Synodal Printing House, on Nikolskaya Street, also dates back to the beginning of the 19th century. These watches have a three-dimensional surface and therefore they allow you to find out not only the time, but also the day of the winter and spring equinoxes.

6. In the center of Moscow there is another sundial, they are located on the shelter building near the Church of St. Louis, located at: st. Lubyanka, 12A

7. Another sundial is located on the pedestrian alley of Cosmonauts leading to the memorial museum of cosmonautics.

8. The newest sundial in Moscow is located on the building of the Russian-Lithuanian school in Hospital lane; e.3.

Of course, it turned out that there are much more sundial in Moscow. After all, after the repair in the Moscow Planetarium, they opened the Sky Park observation site, where various types of sundials are presented. I decided to go to the Planetarium and look at this sundial. There I learned and saw a lot of new and interesting things:

Horizontal sundial of the Moscow Planetarium.

Equatorial sundial of the Moscow Planetarium.

Also in the Moscow Planetarium there is a model of the Samrat Yantra sundial located in India.

Vertical sundial of the Moscow Planetarium.

• Sundial device.

So, let's take a closer look at each part that forms the sundial.

Scales.

The main element of the dial is a scale for registering time. The accuracy of the scale depends on the accuracy of the manufacture of the sundial and the care taken in assembling its parts. In addition, the accuracy of the scale is determined by the size of the sundial (the larger the size, the more accurate the scale can be made). The divisions of the scale are segments of the so-called hour lines. That is, the lines formed by the shadow of the gnomon on the dial of the sundial.

In the photo below, the hour lines are highlighted in color.

Sometimes, in addition to the scales intended for recording time, scales are made on the sundial to measure the azimuth of the sun and the height of the sun above the horizon, as well as a scale of geographic longitude. Azimuth is the angle between the direction of the pole and the direction of some distant object. At the time of true noon, the azimuth of the sun is by definition 180º, and at the moment when the sun is exactly in the west or exactly in the east, its azimuth is respectively equal to 90º and -90º. Most people assume that the sun always rises in the east and sets in the west. Using the azimuth scale, it is easy to verify that this is not the case. Only twice a year, on the equinoxes, the sun rises in the east and sets in the west. The longitude scale allows you to observe the movement of the sun around the planet. When the sun crosses any local meridian, true solar noon occurs on that meridian, the sun occupies the highest point of its daily path and its azimuth is exactly 180º. That is, at this moment the sun is exactly in the south. If the scale of geographical longitude is supplemented with a list of cities in such a way that the name of the city is located opposite the corresponding longitude, then by the shadow of the gnomon it is possible, without resorting to calculations, to find out in which city it is now true noon.

Gnomon.

A gnomon is a material object, and it has a thickness. It should be taken into account when calculating the dial. Breaks are made in the scales, the width of which is equal to the thickness of the gnomon. Strictly speaking, an accurate sundial has two gnomons - east and west. The western is an edge formed by the western and upper faces. Its shadow records the time from sunrise to noon. East is an edge formed by the east and top faces of the triangle. Its shadow records the time from noon to sunset.

How are sundials different from ordinary ones.

The sundial shows true solar time. Wristwatches show mean solar time. The moment when the sun reaches the highest point of its daily path and crosses the local meridian is called the true solar noon. The time interval between two consecutive noons is called a true solar day.

The true solar day is a variable value. Sometimes they are longer, sometimes shorter. Therefore, their parts, that is, hours, minutes and seconds, are not always equal to each other. It is difficult to design a clock mechanism so that it follows the sun exactly, that is, faster one day and slower the next. Therefore, wristwatches do not show solar and some other time, called the average. The duration of the average day, also called civil, is obtained by calculation. Add up the duration of all solar days of the year and divide the resulting sum by the number of days in the year. A civil day, and therefore civil hours, minutes and seconds, is a constant value by definition.

Before the invention of atomic clocks, the most stable unit of time was the sidereal day, defined by the time interval between two successive risings of a distant star. To measure the duration of a solar day, and then by calculations to determine the duration of the average day, according to tradition, it is sidereal time that is used - sidereal hours, minutes and seconds.

• Types of sundial.

Sundial - a device for determining time by changing the length of the shadow from the gnomon and its movement along the dial.

There are 4 types of sundial: horizontal, vertical, equatorial and analemmatic.

but) Horizontal sundial.

These clocks can be seen in many parks and gardens.

watches in Sevastopol; emb. Kornilov

A horizontal sundial consists of a frame (a plane with hour divisions) and a gnomon. The dial is located horizontally relative to the earth's surface. The gnomon is located perpendicular to the frame and is a triangle, the angle of which is equal to the latitude of the place where the sundial is located (for Moscow it is 55 degrees).

b) Vertical Sundial

Clock on the building of the Solovetsky Monastery (Solovki Islands)

IN Vertical sundials are usually located on the walls of buildings. Therefore, the dial is perpendicular to the plane of the earth's surface. And the gnomon is located at an angle equal to the latitude of the place where the clock is located.

in) Equatorial sundial.

Clock on the River Thames (London, England.)

This sundial consists of the same parts as the 2 previous types. Gnomon, mounted on the dial perpendicular to its surface. The dial is set at an angle of 90 degrees, minus the latitude of the area in which the dial is located.

G) Analemmatic sundial

On such a watch there are all the same parts as on the rest, but a man serves as a gnomon here.

The dial of an analemmatic sundial is elliptical in shape. The closer the clock is to the south, the more the ellipse becomes like a circle.

clock on the territory of the nature reserve "Valley of the Setun River"

In the middle of the dial there is a platform lined by months. Since a person stands vertically with respect to the surface of the earth, and not at a certain angle, like a gnomon on a horizontal clock, his shadow will not show the exact time throughout the year, but will gradually shift. To correct this shortcoming, a place is marked on the site where a person should stand so that his shadow shows the exact time. But even in this case, the shadow will show the exact time only in the middle of the month, and there will be a slight discrepancy at the beginning and end.

It is believed that the world's first clock was solar. Their history already has more than one millennium, but when exactly people began to use them is not known for certain. It has been established that in ancient Egypt, Babylon and China, such devices were used earlier than a thousand years BC. The first mention of determining the time by the sun's rays with the help of a gnomon dates back to 1306-1290. BC.

a) Sundial in China.

The first mention of a sundial in China is probably the problem of the gnomon, given in the ancient Chinese problem book "Zhou-Bi", compiled around 1100 BC. e. In the Zhou era in China, an equatorial sundial was used in the form of a stone disk installed parallel to the celestial equator and penetrating it in the center of a rod installed parallel to the earth's axis. In the Qing era, China made a portable sundial with a compass: either equatorial - again with a rod in the center of a disk installed parallel to the celestial equator, or horizontal - with a thread in the role of a gnomon above a horizontal dial.

b) Sundial in Ancient Rome and Ancient Greece.

According to the story of Vitruvius, the Babylonian astronomer Berossus, who settled in the VI century. BC e. on the island of Kos, introduced the Greeks to the Babylonian sundial, which had the shape of a spherical bowl - the so-called scaphis. In the middle of the 18th century, during excavations in Italy, they found exactly such an instrument as described by Vitruvius.

From Greece, the sundial reached Rome. In 293 BC. Papirius Cursor ordered to build a sundial on the wall of the Quirinal temple, and in 263 BC. another consul, Valery Messala, brought a sundial from Sicily.

c) Sundial in Ancient Russia.

In ancient Russian chronicles, the hour of some event was often indicated, which suggested that at that time certain instruments or objects were already used in Russia to measure time, at least during the day. Chernigov artist Georgy Petrash drew attention to patterns in the illumination of the niches of the northwestern tower of the Transfiguration Cathedral in Chernigov by the Sun and to a strange meander pattern. Based on a more detailed study of them, he suggested that the tower is a sundial in which the hour of the day is determined by the lighting of the corresponding niche, and the meanders serve to determine the five-minute interval. Similar features were noted in other temples of Chernigov, and it was concluded that the sundial was used in Ancient Russia as early as the 11th century.

d) Sundial in Great Britain.

The UK is home to one of the most famous and ancient sundial in the world, Stonehenge. This is an ancient observatory that was built in the first millennium BC. Ancient people used Stonehenge as a solar and lunar calendar. Now it is a very valuable attraction.

And in the "Park of Heaven" of the Moscow Planetarium, I saw a model of this ancient observatory.

III. Sundial in the school yard

After I found a sundial in Moscow, studied the device of a sundial and their types, I decided to make my own sundial in the school yard. I decided to make one sundial in our school yard horizontal. As we know, one of the parts of such a clock is a gnomon, which is installed in the center at an angle equal to the latitude of the area. For Moscow, this angle is 56 0 . But if a pin is placed in the middle of the school yard, small children can run and run into it. That is, the installation of such equipment would not be safe for schoolchildren. So I decided to make a removable gnomon. That is, to strengthen it on the board, it will be constantly stored in the teacher's office, and if necessary, under the guidance of the teacher, it can be installed and the time can be checked. But then, just walking in the yard, children without a gnomon will not be able to determine the time. That is, one more sundial is needed, where the person himself acts as a gnomon. As we know, this is an analemmatic clock.

• My double dial watch.

I came up with a new kind of sundial, which I have not seen anywhere else. This is a double dial sundial.

In Moscow, from October to April, the weather is mostly cloudy, the sun rarely comes out. And from November to March, the schoolyard is covered with snow. Thus, during these months, the use of sundial is irrelevant. On the other hand, in the summer, all the children leave for the holidays, no one walks in the school yard. That is, in the summer months, a sundial is not particularly needed. But on warm sunny May or September days, schoolchildren like to run out into the yard during breaks, walk there after school. Children from the extended day group also spend a lot of time outdoors. These days physical education lessons are held on the street; some teachers conduct practical work in the open air. It was at this time that the sundial in the yard would have found its use. And since we have only two months of using the watch, we can not change the site to accommodate the person who decided to use the watch, but make two scales of different colors: one for May and one for September with their own markings. We began to implement this idea in our school yard.

• Sundial manufacturing steps

1. So, at first we looked at our schoolyard for a long time, choosing a place well lit by the sun throughout the day. Such a place was found near the elementary school building.
2. On a sunny day, in mid-May, on Saturday, we went out to the schoolyard. We have drawn the base of our sundial. To do this, we took a thick thread, tied a pencil to it on one side, and chalk on the other. After that, we stuck a pencil into the ground and drew 2 circles with chalk.

3. After we got 2 circles, we painted over the space between them with white paint. It was the May scale.

4. After 2 circles were filled in, we marked all sides of the horizon with the help of a compass.

5. Then we set the gnomon so that its tip points to the south and put a dot in that place so that it is clear how to put the gnomon. On a two-scale sundial, the gnomon, as we already know, is a person, so we drew 2 feet there, on which a person needs to stand in order to find out the time. And every half hour we made marks.

6. After the numbers were marked, we decided to decorate the clock with pictograms in accordance with the daily routine. We drew pictograms using stencils of our own making, and then filled them with paint and spray cans for graffiti.

7. Thus, the horizontal sundial was ready. And on the two-scale sundial, the 1st May scale was ready. We could complete the two-scale sundial only in September.

8. In mid-September, on a sunny day, we completed our sundial. Thus, the September scale appeared on our two-scale sundial.

9. So that schoolchildren understand how to use my sundial, I made a plate with detailed instructions.

And we were very pleased to see that schoolchildren approached the clock, were interested in it and determined the time by it.

IV. Conclusion

Conclusion: I believe that my work meets all the performance criteria:

a) my sundial shows the exact time on sunny May and September days;

b) I think that my sundial is simple and easy to use, besides, it has a plate with detailed instructions;

c) I believe that my sundial will be useful for schoolchildren on sunny May and September days, when students leave school, they can roughly find out the time by standing in the center of a two-scale sundial. And with the help of a horizontal sundial, elementary school teachers, as well as physics and geography teachers, can conduct open lessons on the street;

d) I think that my sundial looks aesthetically pleasing and serves as a decorative element of our school yard.

I really enjoyed working on the project, so I want to make a portable model of an equatorial sundial that teachers can use in their lessons.

Probably few people know that the world's largest gnomon (sundial) is located in the center of the Indian city of Jaipur, which is the capital of the state of Rajasthan. The sundial, called the Samrat Yantra, is the largest of the 14 astronomical devices of the Jaipur open-air observatory built by Maharaja Sawai Jai Singh between 1727 and 1734. It should be noted that the Indian prince, passionately passionate about mathematics and astronomy, created five large observatories in his entire life. However, the unique Jaipur observatory Jantar Mantar ("Magic Device") became a real architectural monument, and in 1948 it was declared a national monument.

The Samrat Yantra of the Jantar Mantara Observatory is the grandest of the 14 open-air stone and brick structures, used as a uniformly running and accurate sundial. In addition to its gigantic size, the Samrat Yantra (“Main Instrument”) is also the most complex astronomical device of the Jaipur observatory, which is not an easy task for a modern layman to understand. Today, like three centuries ago, the ramp of the most important astronomical instrument of the Jantar Mantar Observatory is locked with a gate. During the reign of Maharaja Sawai Singh, he alone had the right to enter the gate and climb the stone stairs to carry out his regular measurements, which looked more like a ritual, and the monumentality of the stone structure only added importance to this process.

The sundial works from sunrise to sunset. The unique astronomical instrument consists of a ramp - a huge triangle leading up a gigantic staircase, oriented exactly to the north and located at 27 degrees north latitude, and two semicircular dials in the form of wings. The arcs of the Samrat Yantra dials are spread at an angle of 90 degrees on different sides of the giant "stairway to heaven", the railing of which, casting a shadow, is the arrow of a giant gnomon. Until noon, the railing casts a shadow on one wing of the dial marked by hours, each of which is divided into 30 parts, in the afternoon - on the second, opposite wing. At noon, when the sun is on the meridian, both scales of the dial are fully illuminated, but this moment is incredibly fleeting. The dial of the largest sundial in the world is similar to the rim of the wheel, the axis of which is the railing. It should be noted that since the upper plane of the rim coincides with the equator, the shadow always glides uniformly over this surface, and the speed of the hand is about 12 cm in 2 minutes - the minimum division of the watch scale.

For a more complete representation of the dimensions of the Jaipur Samrat Yantra, I would like to indicate the true dimensions of this astronomical instrument. The structure, which is based on a huge rectangular triangle of stone and brick, is 70 feet (21.34 m) high. The length of the base of the triangle, the part of the building in contact with the ground, is 114 feet (34.75m). The longest side of a right triangle, the hypotenuse, which is parallel to the earth's axis and oriented to the North Pole, is 128 feet (39m), and the width of the staircase to heaven is 10 feet (3.05m). The dimensions of the Samrat Yantra semi-circular dials are no less impressive with their dimensions, the radius of each of which is about 15 meters.

In Austria on the mountain "Elfer" are presented the largest sundial in the Alpine region. The sundial is an armillary sphere - a series of rings in the plane of the equator. The functioning of the clock depends on the sun casting shadows. Time (stick shadow) and date (ball shadow) are read on the metal strip. The tilt of the earth's axis to elliptical orbit as our planet revolves around the sun, during the year causes the difference between Central European time and real sunny time, which can reach up to 15 minutes. With this sundial, the date can only be read around noon.

Months are shown on a small sundial plate. The sundial has a diameter of 8 meters and is made of radial hardwood, the wood of which is extremely resistant to decay. When the wood dries, its density increases so much that it is impossible to hammer a nail into it.

Tower rises in London Big Ben 96.3 meters high, she wears the world's largest four-sided chiming clock. And the real Big Ben is a large bell weighing 13 tons, which is located at the top. Previously, the tower housed a prison. The only prisoner in its entire history was a woman.

Dimensions: The diameter of each of the dials, lined with 312 panels of frosted glass and located on four sides of the tower, is seven meters. The length of the hour hand, cast from metal, is 2 m 70 cm, and the minute hand, made of copper sheet, is 4 m 30 cm. The height of each digit is only 61 cm.


In the Strasbourg Cathedral of France, the landmark of the temple are astronomical clock . This massive mechanism brought together the skills and knowledge of the best mathematicians, astronomers and technicians of Europe in the 16th century. The clock accurately calculates church holidays. In 1832, a device was added showing the orbits of the Earth, the Moon, and the then-known planets. The slowest rotating mechanism shows the precession of the earth's axis - one rotation takes 25,800 years. Every 15 minutes they announce that there will be movement on the clock.


The height of the clock is enormous. You have to raise your head high to see the topmost dial. At certain intervals, the sound of the opponent is heard, repulsing the blow, and on the upper gallery, figures appear, symbolizing the four ages of human life, and the Angel below turns the hourglass.

The Town Hall Tower in Prague is decorated with famous astronomical clock "eagle" that ring every hour, and figures move around the dial. Dimensions: The diameter of each of the two dials is about 2.5 meters. Fact: Translated from Czech “orloj” means tower clock. Every hour, the skeleton, symbolizing Death, pulls the bell, the Miser rings coins, the Proud admires himself in the mirror, and the 12 apostles begin their procession. According to legend, the master Ganush, who repaired the clock in 1490, had his eyes gouged out so that he could not reproduce something like that.


Clock on Marienplatz in Munich. On the central tower of the town hall there is a chiming clock playing a 15-minute performance. Every day at 11 o'clock, 43 town hall bells begin to beat, windows open, and 32 human-sized figures begin to play scenes from city life. (photo from internet)

The existence of a clock on the main gates of Moscow has been mentioned in the history of Russia since 1585. In 1705, by decree of Peter I, a new clock, bought in Holland, was installed in the Kremlin.


Modern chimes were made in 1851-52. The famous melody of the bell chime of the chimes, which marks the onset of each hour and a quarter, is widely known throughout the world. In November 1917, during the storming of the Kremlin by the Bolsheviks, a shell hit the clock, breaking one of the hands and damaging the mechanism for rotating the hands. The clock has stopped for almost a year. In 1918, at the direction of Lenin V.I., the Kremlin chimes were restored. (photo from internet)

In Venice, St. Mark's Square on the north side rises Clock tower . Above the arch, located above the gate, there is the famous clock, studded with gilded stars against a background of blue enamel. The decoration of the dial is completed by the signs of the zodiac and symbols of the planets. Above the large clock in a niche is a sculpture of the Madonna and Child. Even higher, the Winged Lion, the symbol of St. Mark, attracts attention. At the top of the tower are two bronze statues, called "Moors" for their color, which strike the clock, causing a large bell to ring.

On a sunny day, any pole casts a shadow. To find out how much time, people measured the shadow with steps. In the morning it was longer, at noon it became quite short, and in the evening it became longer again. The pillar, which was used as a clock, was called a gnomon.

Gnomon - a sundial, was the first clock to measure time by the length of the cast shadow. For many peoples, these obelisks served at the same time to venerate the cult of the sun god.

Indian mendicant monks - fakirs turned an ordinary travel stick - a staff into a watch. This staff was octagonal. At the top of each face, a hole was drilled into which a small stick was inserted. To find out what time it is, the fakir raises his staff, holding it by the cord. The shadow that fell from the wand on the edge of the vertically hanging staff showed the time. On the edge of the staff are carved lines indicating hours. But why do you need so many edges? It would seem that one is enough, but the fact is that at different times of the year the visible path of the sun is different. Therefore, the shadow, which depends on the sun in everything, behaves differently in summer and winter. In summer the sun rises higher in the sky than in winter; that is why the shadow in summer noon is shorter than in winter. That is why the staff is made multifaceted. Each facet is marked for one of some seasons and is not suitable for another.

Imagine the ancient city of Babylon about 3.5 thousand years ago Every day from sunrise to sunset at the top of the ancient tower, where the abode of the supreme deity Eilil was, there was a priest on duty and watched the movement of the sun's shadow from the top of the pillar.

As soon as the shadow touched the next line, he raised the horn to his mouth and announced loudly: “Know, free and slaves, another hour has passed after sunrise!”

From Babylon, the sundial spread throughout the world. Previously, clock people ran around the main square of the ancient Greek city of Athens and informed those who wished what time it was. They recognized the time by the only sundial in the city and reported the time for a small coin. The Babylonians taught the ancient Greeks to divide time into equal intervals - hours. They also taught the Greeks to build a new sundial - the first watch with a dial.

In a sundial, a small rod (gnomon) was fixed on a plane (cadran), demarcated by lines - the dial, the shadow from the gnomon served as the hour hand.

Historical sources consider the very first mention of a sundial to be a Chinese manuscript from the Chiu-pi period around 1100 BC.

The first obelisks and pylons, intended in Egypt to measure time, were built, in all likelihood, as early as the 14th century. BC. Until now, such an obelisk 35.5 m high has been preserved on the square of St. Peter in Rome, which was brought there in 38 by Caligula from Heliopolis.

Earlier information about sundial in ancient Egypt is known, for example, the image of a sundial and how to use it on the tomb of Seti around 1300 BC

News of the oldest of the ancient Egyptian sundial dates back to the reign of Thutmose III - the first half of the 15th century. BC. Egyptian gnomons were highly inaccurate timekeeping instruments. They showed the time correctly only twice a year - on the days of the spring and autumn equinoxes. Later, under the influence of the Greeks, the Egyptians began to build sundials with special scales for different months.

In the Middle Ages, a sundial could look unexpected. On the square, leaning on a scythe, stood a sculpture of an old woman-death, and the shaft of her scythe was a gnomon of a horizontal clock.

Varieties of sundials were very diverse. In addition to horizontal clocks, the Greeks also had more advanced vertical sundials, the so-called hemocycles, which they placed on public buildings.

There were also mirrored sundials that reflected the sun's rays with a mirror onto a dial located on the wall of the house.

Sundial met not only in the form of hours located in the open air - on the ground. columns, etc., but also in the form of a small table clock.

Approximately at the beginning of the XVI century. window sundial appeared. They were vertical, and their dial was the surface of the window of a temple or town hall. The dial of these clocks, which are quite common in Germany and England, usually consists of a mosaic panel filled with lead. A transparent scale made it possible to observe the time without leaving the building.

There were also portable sundials, but they showed the correct time if they were correctly installed, i.e. oriented.

The first creators of a sundial with a corrective compass include the astronomer Regiomontanus, who worked in the middle of the 15th century. in Nuremberg. The combination of a sundial with a compass has led to sundial ubiquity and portable, pocket or travel models.

In the 15-16 centuries. used a pocket sundial. When the lid of the box was lifted, a cord was stretched between it and the bottom - a gnomon. On the bottom - a horizontal dial, and on the lid - vertical. The built-in compass made it possible to turn the gnomon to the north, and a miniature plumb line - to keep the box horizontal. The shadow of the gnomon showed the time on both dials at once. A special bead attached to the gnomon marked the date of the year with its shadow.

In the past war, in the humid and hot wilds of Africa, where soldiers fought, modern mechanical watches hopelessly broke. And a simple small plastic sundial was not afraid of moisture, heat, or dust. To set the correct position, the pocket sundial must have a built-in magnetic compass or turn north on its own.

The largest sundial "Samrat Yangra" has a gnomon length of 27 m and a height of 36 m. They were built in 1724 in Jaipur, India.

The most modern option!

In the US, a digital sundial has been patented that does not have moving parts. Depending on the position of the sun, sunlight, passing through the filters (in the form of numbers), displays the time on the scoreboard with an accuracy of 10 minutes.

On the road leading from St. Petersburg to Moscow, stone milestones still stand here and there, erected under Catherine II. On the pillar, on one side, there is an inscription: “22 versts from St. Petersburg”, and on the other, a plate with an iron triangular plate in the middle and Roman numerals around. Roman numerals represent hours. And the arrows are replaced by the shadow of the plate. The shadow moves like a clock hand and shows the time.

The sundial is still alive, although it has a big drawback: at night and in cloudy weather they are useless.