SUNDIAL
an ancient instrument for measuring time by the sun. This is probably the oldest scientific instrument that has come down to us unchanged and represents the first application by man of his knowledge of movement. celestial bodies. Although a wide variety of sundials are known, they can all be divided into several basic types. The most common clocks of the horizontal type; they can be seen in many parks and gardens. Clocks with a vertical dial are usually found on walls oriented to the cardinal points. A rotated dial is made for vertical clocks placed on walls that are not oriented to the cardinal points. And the deflected and inclined dials are inclined, respectively, from the observer and towards him. They are commonly found on multi-faced watches that combine three or more dials and are often cube-shaped; they are placed on the roofs and crests of the walls, oriented to the cardinal points. Rotated-deflected and rotated-tilted dials are placed on buildings that are not oriented to the cardinal points. For equatorial and polar watches, the planes of the dials are parallel to the planes of the equator and the polar axis, respectively. Armillary watches have an equatorial dial; they are often used for decorative purposes. They contain from two to ten rings, representing great circles of the earth and celestial spheres. Hour divisions are plotted inside the equatorial circle, and the rod representing the polar axis serves as the shadow-casting gnomon.
The oldest sundial known today was made around 1500 BC. They are made of stone in the form of a bar about 30 cm long with a vertical T-shaped pommel at one end. Time was counted according to the serifs applied on the bar at unequal intervals. The clock was set horizontally on a plumb line. The T-shaped end turned to the east in the morning, and to the west in the afternoon. The shadow from the upper edge of the "T" indicated the time. These and other ancient solar instruments showed "unequal hours" resulting from dividing the time from sunrise to sunset into a fixed number of parts. Since the duration daylight hours during the year, the length of the hour changes, and the length of the hour also changed: in summer it was longer, and in winter it was shorter.
TYPICAL GARDEN SUNDIAL. They show the true solar time, which differs from standard time in different ways in different seasons of the year. "Gnomon" - common name for a shadow-casting indicator, and "pointer" is the edge of the gnomon that is being counted. For accurate time measurement, the angle between the pointer and the horizontal dial must be equal to geographical latitude places.
It was not difficult to make such a watch. Many of them had hour lines for certain days years separated by about a month, as well as for the dates of equinoxes and solstices. The hour marks for each day were obtained by connecting the points on which the given hour the shadow cast by the gnomon on the days of the equinoxes and solstices. Around the beginning of the Christian era, the principle of the oblique gnomon was discovered, which made it possible to introduce "equal hours", which provided more accurate time keeping. It was found that if the rod of the gnomon is directed to the pole of the world, then it becomes, as it were, the axis of that circle parallel to the equator along which the Sun revolves. Dividing it into 24 equal parts, we got hours of the same duration. After that, the manufacture of accurate and evenly running sundials became a simple geometric and trigonometric exercise. The evolution of the sundial went hand in hand with the development of mathematics and astronomy. However, for many centuries, only craftsmen familiar with gnomonics owned the art of creating sundials. From the 14th to the 18th century, many artisans showed ingenuity and skill in making high-precision pocket sundials, which became watchmaking gems. The appearance of mechanical clocks did not abolish until the 18th century. using a sundial to keep time. Sundial makers kept pace with mechanical clock designers by inventing solar instruments to determine "mean time". When it was introduced standard time", sundials were adapted for this as well. (The standard time is the mean solar time at a certain meridian.) In the late 19th and early 20th centuries, many very accurate sundials were made to determine standard time, called heliochronometers.
Clock building. In order for a sundial to be useful, it must be built in a suitable place. The latitude of the place must be known, as well as the position relative to the horizon and the meridian of the site or surface on which the hour lines will be drawn.
SUNDIAL FOR "MEDIUM TIME". In alidade (goniometer with sights) Sunshine falls on the analemma (figure eight, showing the seasonal deviations of the sun). When the alidade is set so that the light point falls on the mark given day, the pointer shows mean solar time. So these watches "automatically" compensate for the seasonal unevenness in the movement of the sun.
The most important parts of a sundial are the dial, i.e. a surface on which hour lines are applied, and a gnomon to cast a shadow. Pointer, i.e. that edge of the gnomon, whose shadow indicates time, is always directed to the pole of the world. The height of the pointer is the angle at which the pointer is inclined to the dial, and the center of the dial (the point from which the hour lines diverge radially) is the point of intersection of the pointer with the plane of the dial. Node is singular point on the pointer, the shadow of which is used to read the height, declination and azimuth, as well as time. Methods for determining time by the sun. There are three methods for determining time from the sun: by measuring its hour angle from the meridian, as in a conventional garden sundial; by measuring its height above the horizon and by its azimuth (the angle measured in the plane of the horizon, between the direction to the south point and the vertical circle passing through the sun), which requires a vertical pointer from the gnomon. Most stationary sundials measure the hour angle. The other two methods are often used in portable watches.
There are also three ways to indicate the time: a shadow, a light point and a magnetic needle. Most clocks use shade. Light is rarely used in stationary clocks. And in portable devices, all three methods are used. Watches with a magnetic hand are of two types. In the first, hour marks are applied to the compass case, which is usually given square shape. By turning the case so that the shadows on its side faces disappear, the time is read in the direction of the arrow. In instruments of the second type, hour marks are applied to an elliptical belt, which moves in accordance with the day of the year, as in many azimuth clocks. In this case, the body is also rotated until the shadow on the side faces disappears and the time is read in the direction of the arrow. Clocks of this type are more accurate; their error is determined only by the fact that the magnetic needle deviates from the true direction to the north.
Special sundial. As a rule, a sundial is arranged in certain place, but you can also make a universal watch for use anywhere. Sometimes they are made only to indicate noon or public holidays. Nowadays, the most common are horizontal clocks with a triangular gnomon and vertical clocks on the walls of houses. However, many other designs can also be found. Making portable sundials has now become a popular hobby.
see also HEAVENLY SPHERE ; TIME .
Collier Encyclopedia. - Open society. 2000 .
See what "SUN DIAL" is in other dictionaries:
Sundial, an instrument that began to be used about 5000 years ago in the Middle East to determine the time of day. Traditionally, a sundial consists of a short base with a flat top, on which is mounted a gnomon, a column, ... ... Scientific and technical encyclopedic dictionary
They consist of a dial and a rod, the shadow of which, moving along the dial due to the movement of the Sun across the sky, shows the true solar time ... Big encyclopedic Dictionary
- (Sun dial) a device for determining the true solar time. Consists of dial and stem. When illuminated by the sun, the shadow of the rod indicates the true solar time on the dial. Samoilov K.I. Marine vocabulary. M. L .: State Military ... ... Marine Dictionary
This term has other meanings as well. Sundial(values). Wall (vertical) sundial in the Solovetsky Monastery. Shooting time 13:40 Moscow time ... Wikipedia
An instrument used to determine time by the sun. S. hours consist of a rod or plate that casts a shadow, and a dial on which the shadow falls, indicating the true solar time. Depending on the location of the plane of the dial ... ... Great Soviet Encyclopedia
A device for determining the time by the sun. It usually consists of a dial, located. vertically, horizontally or perpendicular to the axis of rotation of the Earth, and a rod or plate that casts a shadow on the dial (see fig.). The position of the shadow indicates ... ... Big encyclopedic polytechnic dictionary
They consist of a dial and a rod, the shadow of which, moving along the dial due to the movement of the Sun across the sky, shows the true solar time. * * * SUNDIAL A SUNDIAL consists of a dial and a rod, the shadow of which, ... ... encyclopedic Dictionary
A sundial consists of three parts: a gnomon, that is, an object that casts a shadow, a dial on which this shadow falls, and the sun itself. The lines on the dial, the shape and size of the gnomon are calculated individually for each watch, depending on geographical coordinates their installation locations.
A sundial is an astronomical instrument that measures the altitude, azimuth and declination of the sun. The dimension of these quantities is degrees of arc. At our discretion, we can give them different physical meaning. So, by the value of the azimuth and the height of the sun above the horizon, we can measure time. And by the value of the declination - to register the dates of the transition of the sun from one zodiac constellation to another, determine the onset of the equinox, solstice, or any other date, such as a birthday.
The location of the lines on the dial of a sundial depends on the orientation of the dial relative to the celestial pole, the mathematical horizon, and celestial equator. The dial can be drawn anywhere, for example, on a spherical surface.
Even though sundial designs are extremely varied, most people assume that a sundial is a disc to which a triangle is attached. In part, this is true. This is what the most common horizontal sundial looks like.
Consider how a typical horizontal sundial works.
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.
Previously, before the introduction of standard time, there was only one scale designed to register local time - that is, the time on the meridian passing through the place where the sundial was installed. Now on the dials you can see two or even three scales. One is for registering local time, the second is for registering standard summer time, and the third is for registering standard winter time. This is done so as not to confuse the user with calculations. It should be borne in mind that this is not different types time, but just different ways measurements of the same.
There are special cases when additional scales are placed on the dial. The need for this arises when a sundial is installed in one time zone, but is intended to register time in another time zone, thousands of kilometers away from the installation site. For example, as on this sundial, which is installed in Umea (Sweden), but records the time in Moscow.
Sundial for GMT+3 and GMT+1 time zones
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 scale of the sun and a scale of the height of the sun above the horizon, degrees of arc.
Azimuth is the angle between the direction of the pole and the direction of some distant object. In gnomonics, unlike geodesy, the azimuth is traditionally measured from the direction to the south geographic pole. This means that at the moment 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, does the sun rise in the east and set in the west.
A scale measuring the height of the sun above the horizon is usually placed on the dial of a sundial designed to serve study guide in geography and astronomy. AT ordinary life, in everyday life, there is no need to know what is in this moment the height of the sun above the horizon. But on the sundial installed on the school astronomical site, such a scale is appropriate.
Geographic longitude scale, supplemented by city names
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.
Equation of time and analemma.
On the face of a sundial or next to sundial often put a table of the equation of time (or its graph) and an analemma. To understand what it is, some explanation is necessary. The fact is that the readings of a sundial coincide with the readings of a wristwatch only four times a year - on April 15, June 12, September 1 and December 24. On the rest of the year, the sundial either advances or lags within (+ 14) - (-16) minutes. The reason is that the sundial measures the true, objective existing time, whereas wrist watch they measure the so-called average time, specially invented by people to simplify the process of measuring it. In order to find out the average time from the true time measured by a sundial, a special correction called the equation of time should be added to their readings. The equation of time is the difference between the readings of a wristwatch and a sundial. AT special literature it is usually referred to as µ or EoT. AT different days year value µ It has various meanings. Expressed graphically dependence µ from calendar date called a graph, nomogram, or time equation table.
Pie chart of the equation of time and an analemma designed to calculate the average time from the readings of a sundial.
The earth revolves around the sun in a plane called the ecliptic. The axis of rotation of the earth is directed to the north and is inclined to this plane at an angle of approximately 23 degrees. This means that for half a year we see that the sun is below the ecliptic. At this time, it is winter in the northern hemisphere. During the other half of the year, we see that the sun is above the ecliptic. At this time, it is summer in the northern hemisphere. The height of the sun above the ecliptic expressed in degrees of arc is called the declination. ρ . Graphically pronounced dependence equations of time µ from the decline of the sun ρ called an analemma. In coordinates ρ, µ the analemma is a beautiful figure-eight curve.
Horizontal sundial with a table of the equation of time and an analemma along the hour line. On this sundial, the analemma is used as a tool for checking mechanical, electronic or any other watch.
When applied to a sundial, the analemma can be used in two ways. The first way is that points corresponding to calendar dates are marked on the analemma. Then, if we know what date it is today, we can use the coordinate µ determine how many minutes on that day must be added to the readings of the sundial in order to find out what time it is in terms of the generally accepted average time. At the same time, along the coordinate ρ , we can find out the declination of the sun.
A graph of the equation of time can be carved out of stone and placed next to a sundial as a separate piece of art.
The second method does not require knowledge of the current calendar date. In this case, a specially calculated analemma, divided into segments corresponding to calendar dates, is placed along one of the hour lines. At the moment when the shadow of the nodus (about it below) crosses the analemma (not hour line, sic!), the readings of the sundial coincide with the mean time, and the point of the analemma at which the shadow of the nodus crosses it corresponds to the calendar date. An analemma arranged in this way is very convenient to use for checking mechanical watches and for determining the current calendar date. If the size of a sundial is large enough, and the pairing of its parts is accurate, we can break the analemma into 365 sections and thus endow the sundial with another function - to serve as a perpetual calendar.
The shadow of the nodus crosses the "eight" of the analemma twice. Therefore, the use of the analemma as a tool for checking watches and for determining the date assumes that the user is aware that the analemma distinguishes between two parts - winter and summer, and that they are not symmetrical to each other. Graphically, they look like S-shaped curves mirrored relative to each other. The winter part is used between the autumn and spring equinoxes, the summer part is used between the spring and autumn equinoxes.
For more detailed acquaintance with the concept of analemma, you can refer to the educational video material of Ivan Korolev.
There are dozens of ways graphic image these dependencies and a great variety of methods for their implementation in the material. Here is some of them.
The graph and table of the equation of time can be made of stone and of gold-plated, patinated or aged non-ferrous metal.
Gnomon.
A gnomon is an object that casts a shadow on the dial and serves to record the time. On a horizontal sundial, it usually has the shape of a triangle, and its angle of inclination corresponds to the geographic latitude. The plane of the triangle is parallel to the local meridian, and its upper side is parallel to earth's axis and is always directed to the north celestial pole. (Of course, only in the northern hemisphere).
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 a rib 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.
Gnomon made by plastic casting. Bronze, patinated.
Gnomon with textured patinated surface. Brass.
Gnomon with nodus. On the east side of the gnomon is engraved a phrase from the book "Steel Rat goes to the army" by Harry Harrison. Brass, 999 gold.
One of the faces of the gnomon is curvilinear. This is done, apparently, not only for aesthetic reasons, but also in order not to confuse which face should be used to register time. The plane of the gnomon need not be solid. It can be made by injection molding, waterjet cutting or any other method depending on preference. It is only important that the edge intended for recording time be strictly straight and located at the calculated points of the dial.
Gnomon nodus. On the western face of the gnomon, a phrase from the text of the article by M.V. Lomonosov "On the improvement of telescopes" in 1762.
There is usually only one gnomon on a sundial. The exception is the so-called Ottoman sundial. Two gnomons are installed on them. One is for recording the time, the other, smaller, is for determining the time of Islamic prayers. But there are exceptions. For example, on this sundial, the large gnomon is designed to record the time, while the small conical gnomon is designed so that once a year, on the owner’s birthday, the shadow from the top of the cone follows a specially calculated anniversary line.
Horizontal sundial with two gnomons. On the birthday of the owner of this sundial, the shadow from the top of the conical gnomon follows a specially calculated line.
In very rare cases more than two gnomons are installed on the sundial. So, on this sundial there are three dials, each of which is equipped with its own gnomon. One of them is designed to measure the true local time on the meridian of the installation site, the other is designed to measure the true standard time, and the third is to measure the azimuth of the sun.
Sundial with three gnomons.
Nodus, declination lines, jubilee line.
Nodus (translated from Greek - knot) is such a point on the gnomon, the shadow of which corresponds to the declination of the sun. The declination is the height of the sun above the ecliptic. The ecliptic is the plane in which the earth revolves around the sun.
The nodus is usually made as a mark on the polar face of the gnomon.
Each day of the year corresponds to a certain value of the declination of the sun. As the sun travels from east to west on its daily course, the shadow of the nodus moves across the dial from west to east. The trajectory of the shadow of the nodus is unique for each day of the year and does not change noticeably over the course of centuries. This trajectory is called the declination line.
Decline lines. The dial is engraved with declination lines corresponding to the dates of the sun's transition from one zodiac constellation to another.
On International Museum Day, the shadow of the nodus follows a specially calculated commemorative declination line.
The declination lines on the dial can be calculated for any date. But usually they are calculated for dates that have astronomical meaning. For example, for the days of the equinox and solstice. As the Earth makes an annual revolution around the sun, the starry background of our star changes. Since time immemorial, it has been divided into 12 sectors called zodiac constellations, and many people still tend to consider the transition of the sun from one zodiac constellation to another as a significant astronomical event. If the declination lines on the sundial are calculated for each of these twelve sectors, then the sundial will have one more function. In addition to time, they will register the date of the change of zodiac constellations.
During the year, many events take place in the life of every person. Some of them are subjectively much more important than the change of zodiacal months. The declination line of the sun, calculated for such a day, which is of particular importance in a person’s personal life, is called the jubilee line.
Several anniversary declination lines can be placed on one dial. One for each family member.
Usually the anniversary line is calculated for the wedding day or for the birthday. But there are many other events worthy of comparison with the position of the Earth in its orbit. For example, the day a house is completed, the day a dissertation is defended, the day a poem is published are all very worthy occasions to celebrate every year with a sundial. On one dial, you can put several anniversary lines for each family member. Or you can make several dials for each of them on one sundial.
Every year on the same day sun shade follows along a specially calculated anniversary line. This will continue as long as there is solar system. That is, in the next four and a half billion years.
What is the difference between a sundial and a conventional mechanical watch?.
The sundial shows true solar time.
Wristwatches show mean solar time.
The moment the sun reaches highest point its daily path and crosses the local meridian is called 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 year and divide the resulting amount by the number of days in a year. Civil day, and therefore, civil watch, minutes and seconds, is a constant by definition.
Before invention atomic clock, the most stable unit of time was considered sidereal day, determined by the time interval between two successive sunrises 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 precisely sidereal time — high points, minutes and seconds.
The comparative length of the day, expressed in average time, is as follows:
Mean solar (civil) day
24 h 00 m 00 s
true solar day
24 h 00 m 00 s ± 17 m
sidereal day
23 h 56 m 4.09 s
The axis of our planet is inclined to the plane of its revolution around the sun by 23°. In addition, the orbit of our planet has an eccentricity, which means that the speed of its revolution around the sun is not constant. For these two reasons, the point in time that falls exactly in the middle of the civil day and is called mean solar noon coincides with true solar noon only four times a year. On other days, civil noon either leads the true solar noon, or lags relative to it. The same applies in general to any moment of time, and not just to noon.
difference between true and mean sunny time called the equation of time. In order to obtain the readings of wristwatches from the readings of a sundial, it is necessary to take into account the equation of time. In addition, adjustments for standard time, daylight savings time, and, if the latter is introduced, for daylight savings time are usually required.
Ordinary watches help to decide practical matters Don't be late for work, wake up on time. This is very useful thing- regular hours. In a world where train schedules and gas prices are more real than Kepler's laws themselves, you can't live a day without a regular clock. Nevertheless, the results of evolution cannot be canceled and our bodies continue to live according to the true solar time and continue to remember how our distant ancestors felt, not yet separating time from space, but themselves from nature and happy for this reason alone.
The sundial helps us to more moderately assess our role in this world. They help us remember that the Earth is a very small planet with limited resources, that it revolves around yellow star medium-sized, and this star itself is just one of a great many similar components of our small homeland— The Milky Way Galaxy.
The history of sundial 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 using a special device dates back to 1306-1290. BC.
Any sundial has a dial with a scale and hour hand called the gnomon. At the same time, according to their orientation, sundials are divided into horizontal, vertical and equatorial. There are many modifications of them, such as stepped, ring, plate, mirror, bifilar and others.
A sundial is not necessarily a disk having a perpendicular gnomon. So, the dial can be a hemisphere or a ring. universal equatorial clock can be used at all latitudes. Their design involves two perpendicular each a friend of the ring and the gnomon. To determine the time, you must set the latitude on the scale on one of the rings and set the date. Then the clock turns around vertical axis, until a dot showing the time appears on the dial. At this moment, one ring is oriented north along the meridian, and the second is parallel to the plane of the equator.
In a horizontal sundial, the plane of the dial is not perpendicular to the gnomon, which must be parallel to the earth's axis, and also point to the north, that is, the angle between them equal to latitude terrain. The horizontal clock is convenient and easy to install. To use them at a different latitude, it is enough to change the angle and direct the gnomon to the north.
In ancient Egypt, they were designed different models sundials, for example, with a horizontal scale that made an angle of 90 degrees with the plane of the local meridian, and their gnomons were obelisks, the height of which usually reached several meters. In order to find out the time from them, the direction indicated by the shadow from the gnomon was used. Another sundial, called "step", had two surfaces, tilted to the east and west, and divided into levels. When the sun moved, the shadow moved from one step to another, and time was determined by its length.
AT Central Europe Until the 15th century, wall-mounted vertical sundials, the gnomon of which was horizontal, were widely used. True, the accuracy of determining the time on them was low.
At the same time, there were several variants of road chronometers, for example, ring sundials. They consisted of two rings, in one of which there was a hole for the passage of the sun's ray, and the scales of months and hours were applied to the other. There were also plate clocks, in constructive solution which included two, sometimes three, identical records that had rectangular shape and fastened together, while a compass was installed on the bottom.
There is a description of medieval octagonal sticks with four through holes in the handles, into which metal rods had to be inserted to determine the time. Around the same time, window chronometers appeared. They were vertical. The principle of operation of the sundial was to use the window of the town hall or temple as a dial with a translucent scale applied. This made it possible to find out the time while being indoors. A mirrored sundial used a sunbeam reflected by a mirror, which they directed onto the wall of the building where the dial was located.
Maxim Lugovoi, Anna Razilova, Vasily Pantyushin
Razilova Anna
Pantyushin Vasily
Project manager: Pravdina Elena Anatolyevna
(mathematic teacher)
Objective:
Development cognitive interest, creative activity of students.
Introducing children to the history of the development of sundial.
Tasks:
Skill development independent work, work on the algorithm, under the guidance of a teacher, work in pairs, adequate self-esteem ability to plan their activities.
· Development of harmonious perception of the surrounding world, diligence, responsibility, activity.
Project theses
"Sundial"
- Ancient ways of measuring time.
- Sundial- a device for determining the time.
- The simplest sundial.
- The date of the sundial.
- Clepsydra.
6. Munster - "father of gnomonics."
7. A simple way to measure time in France, southern Germany and some other places was well known even in the 19th century.
Download:
Preview:
Sundial
The oldest ways of measuring time were known for 2000 years BC, and their development continued until the first centuries of modern times. Chronometric instruments of that period are sometimes called the simplest, their era ends first. important improvements mechanical watches with wheel gear. This includes many types of sun, water, fire, hour and other clocks, which, as important elements developments played a significant role in the history of chronometry.
Sundial - device for determiningby changing the length of the shadow fromgnomon and its movementdial . The appearance of these watches is associated with the moment when a person realized the relationship between the length and position of the sun's shadow from certain objects and the positionsun in the sky.
The simplest solarwatch show , and not local, that is, they do not take into account the division of the Earth into. In addition, the simplest sundial does not take into account. You can use the sundial only during the day and in the presence of the sun. At present, the sundial is practically not used for its intended purpose and has given way to various types othershours .
The oldest instrument for determining time wasgnomon . The change in the length of its shadow indicated the time of day. Such a simple sundial is mentioned inbible . According to the stories of Greek writers, real sundials, i.e. special instruments that indicated daylight hours, were borrowedGreeks at Babylonians .
The exact date of the appearance of the sundial, which in its original form had the shape of an obelisk, is unknown. Some historical sources consider the very first mention of a sundial to be a message about them in a Chinese Chiu-pi manuscript of the period around 1100 BC. .). In his manuscript, he mother tongue reported that with their help the Chinese easily established the summer and winter heights of the Sun. The oldest surviving written record of sundials, dating back to 732 BC, is found in the Bible, in the twentieth chapter of the Book of Kings. Ahaz's sundial here refers to the obelisk sundial of King Ahaz, who lived around 732 BC. Discovery of ancient Egyptian sundials from the 13th and 15th centuries. BC. testifies that the actual period of the occurrence of the sundial was much earlier than it follows from the written monuments known so far.
The date usually given is 3500 BC. It was then that the Babylonians were the first to come up with a sundial: they began to strengthen a small rod on a flat board (or hemisphere) demarcated with lines - this was the dial of the sundial, and the shadow from the rod served as an hour hand. Just? Of course. Relatively accurate for that time? Yes. Only one drawback is clear to everyone - all this is good only during the day and in more or less sunny weather ...
Well, at night, the sundial was replaced by clepsydra ("water thief") - this is how the Greeks called the water clock, borrowed from Babylon or Egypt. And in China they were even earlier. It was at first a simple metal or clay, and then a glass vessel, which was filled with water. Slowly, drop by drop, water flowed out, its level dropped and the divisions on the vessel indicated what time it was.
By the way, have you ever wondered why? regular hours the arrows go, what is called "clockwise" (pun intended;))? But because the sun's shadow from the gnomon on the sundial also goes in the same direction. That's why modern clock and adopted this movement from their ancestors. But if the sundial were invented in southern hemisphere, it would be the other way around. Great!
Arab astronomers (, , ) left extensive treatises ongnomonics , or the art of building a sundial. Based on the rules of trigonometry
In the Middle Ages, many people were engaged in gnomonics. Lived at the beginning of the 16th century.Munster He was recognized as the "father of gnomonics".
The gnomon, a vertical obelisk with a scale marked on the ground, was the first sundial to measure time by the length of its shadow. The fact that these obelisks served the Egyptians at the same time to venerate the cult of the sun god is evidenced by the records of ancient writers. These sacred obelisks stood, as a rule, in front of the entrances to temples. 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.
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.
However, let us take into account that under the dominance of the agrarian system and handicraft technology (whether in ancient world or in the Middle Ages) there was no need to divide time into small segments and accurately measure them, as now. People determined the time by the natural illumination of the Sun, long summer days and short winter days, equally divided by 12 hours, and therefore summer and winter hours were different.
Among the common people, the custom has spread to measure time by the length of the shadow from own body. The knowledge of time was very important for the Greek, since, in addition to the term of his labor duties, time indicated the approach of the desired moment for refreshment with food and for rest.
But people also sought out primitive ways of measuring time with the help of the Sun; sometimes the only "tool" for this was human hand. The first reports of such "clocks" refer to early XVI century. left hand turned palm up, and her pointing up thumb served as a shadow arrow. Depending on the length of this shadow in comparison with the rest of the fingers of the hand, one could roughly determine the time. This simple way of measuring time in France, Southern Germany and some other places was well known even in the 19th century.
Let it not seem to you that the sundial is an archaic knowledge. Let it be more convenient to use a small shiny dial on your hand, but a sundial built in your dacha (villa, cottage, etc :)) will look very cool and will surely cause surprise and admiration among your neighbor friends - after all, they have such and such for sure not.
Most people think of a sundial as an infinitely outdated ancient method of keeping time. After all, everyone is already accustomed to the Julian calculus, the uniformity of time calculation by mechanisms and electronics. The question is, why use a sundial in the age of high technology?
But the thing is that thanks to the Sun, you can get the true time of a given latitude, and not the average indicator. After all, the biorhythms of all living beings work according to thousands of years of proven schemes, which, before directive regulation with winter-summer transfers shooter "no business". Astronomical cycles play here key role. The rotation of the earth around the sun and around own axis, lunar month (the rotation of the moon around the axis of our planet) are the most important of them. Once upon a time, man lived in complete harmony with natural rhythms, synchronizing his activities to the cycles of the sun.
You can buy a sundial in the newidea-shop.ru online store, which is part of the NOVAYA IDEA group of projects.
And here comes the so-called technosphere, restructuring the way of life of people. We no longer admire the splendor starry sky, we do not consider the days of the equinox and solstice sacred, like our wise ancestors. And they began to wake up with an alarm clock, and not with the sun. Only a few of us greet the luminary, mostly yogis (Surya Namaskur) and athletes.
This article will cover some basic questions on the topic of sundial.
What is a sundial and how does it work?
A sundial is an astronomical measure of the declination and azimuth of the sun. Their simplest varieties consist of a pointer (gnomon - in ancient Greek) and a dial. True time can be calculated by measuring the length and movement of the shadow cast by the gnomon on the surface of the dial.
Why do modern people need a sundial?
The attractiveness of the sundial in technocratic modernity has not diminished in the slightest. Installed in a city park or elsewhere, they make it more beautiful and, as it were, majestic. Watching the passage of natural time is quite unusual and exciting, many people like to be photographed against the background of the clock. And what makes them so special?
landscape design suburban area acquires a very special charm after the installation of a sundial. They make the perfect keepsake for loved one or business partner. Interesting topics can be used in watch design: family coats of arms, bright memorable mottos, appeals, company logos.
Memorable dates
After certain calculations, it is quite realistic to anticipate with high accuracy the time indication shown by the gnomon on the dial. Therefore, we can design a sundial, marking the desired date for you - any date of your choice: birthdays, family anniversaries, company foundation dates, etc.
Sundial making
Materials for creation can be very different. Before designing a sundial, there are many factors to consider: landscape design, architectural features of the building, environment and, of course, the preferences of the customer himself. The choice is also made depending on the shape and size of the watch.
In parks and home gardens, steel, stone, concrete, and wood are commonly used; when creating sculptures, stainless steel, bronze, and brass are used. For small gift and "corporate" sundial - noble wood, marble, brass.
Where is the best place to buy and order a sundial?
In company " New idea » there are gnomonics enthusiasts. This is not the science of little dwarf men: gnomonics is the study of sundials. For them, the design and manufacture of a sundial is a great joy of aesthetic and creative achievement. Create for you 100% exclusive custom sundial bring great satisfaction to the employees.
Trust complex calculations and the manufacture of sundial should be professionals who are able to analyze the place of the future installation and not make mistakes in the calculations. Alas, many sellers are completely uninterested in delving into the essence of the issue, so they offer only souvenir and decorative sundials. These products are just imitations of conscientiously made ones. They serve more as an element of interior design or a country plot. It should also be taken into account the fact that the sundial is strictly tied to a certain area, where it will be used.
Varieties of sundials
Attempts to introduce a classification of sundials began as early as Ancient Rome. The then-famous mechanic and architect Vitruvius described about three dozen of their types. In terms of the design of sundials, they differ, firstly, in orientation, and secondly, in the shape of the gnomon and dial.
Polar clock with a horizontal dial
The most common sundial at the moment is the polar gnomon clock. In watches of this type, the gnomon is parallel to the axis of rotation of the earth and is oriented in the direction of the polar star. The angle of inclination of the gnomon φ is equal to the latitude of the location of the sundial, respectively, at the poles the gnomon will be located vertically, and horizontally at the equator. These sundials are often also called park clocks. They can be placed on any flat surface suburban area or park, not shaded by trees or other buildings.
To date, the most common sundial with a polar gnomon (pointer). It is located parallel to the earth's axis of rotation and is oriented to the North Star from the constellation Ursa Minor, located near the North Pole. The angle of inclination of the gnomon is equal to the latitude of the location of the clock: vertically - at the poles, horizontally - at the equator. This type of sundial is also called a park sundial. It is convenient to place them on any unshaded flat surface.
Polar vertical dial
Such clocks are mainly installed on the facades of buildings. Magnificent monuments of architecture with ancient sundial have been preserved. With strong shading by trees, placing them on the facade is the best solution. It is best when the facade is located strictly to the South. If the building deviates from the cardinal points, then additional calculations should be made to take into account the angle of deviation.
This is a polar watch with a polar gnomon-axis located on the dial, parallel to the plane of the equator. The dial is divided into 24 equal parts. The shadow indicating the time moves at a speed of 15 degrees per hour. With the correct location (angle of the gnomon = latitude of the area), this watch will be universal.
Taking into account the winter location of the Sun (below the equatorial plane), the time readings in winter are read in the opposite direction, and the time scale opposite side numbered counterclockwise.
This is a polar clock in which the gnomon and the dial are parallel to the axis of rotation of the planet. The design has one drawback - the limited range of the displayed time (from 7 to 17 hours). This is eliminated by changing the angle of the dial (east or west), which allows you to expand the range of morning and evening time. A gnomon can be a rod and a plate, perpendicular to the plane dial. It is good to put some kind of phrase, drawing or sign on the plate.
armillary sphere
This variety combines the advantages of equatorial and polar sundial, but without their disadvantages. The same dial all year round shows the time in wide range values. The time scale is located on a strip lying in the equatorial plane, as in an equatorial clock. An armillary sundial can also act as a calendar, showing the declination of the Sun (usually for the moments when the luminary enters a certain zodiac constellation).
Solar vertical clock, analemmatic
One of the most ancient types of sundial is one in which the observer himself is a gnomon. The proportion of a person's height to the length of their feet is approximately 1:6. The length of the shadow determines the angle of the Sun. This takes into account the fact that the shadow is cast in different directions in different time year, except at midday, when it falls due north. The dial is an ellipse lying in horizontal plane. In the center of this ellipse is the marking of the seasons. Gnomon is installed in right time in right place, allowing you to determine the true time. Everyone, if desired, has the opportunity to determine the time with their own shadow.
It is curious that if a polar gnomon is added to the dial, then when the readings of the two gnomons are combined, the orientation of the clock will be reduced to this offset.
In this variety, two subspecies are distinguished - a cylindrical clock and a hemicycle. Cylindrical are a vertical cylinder-dial and a gnomon horizontally fixed in the upper part. The horizontal gnomon pointer is fixed on a rotating stand that rotates along the axis of the cylinder to the position of the current month. The shadow falls vertically, indicating the temporary markup. Since the clock shows time depending on the height of the Sun, which is the same twice during daylight hours, one clock shows both morning and evening time.
The hemicycle works on the principle of a sundial with a polar gnomon, indicating the true time and declination of the star. The dial is divided into equal intervals time. Hemicycles first appeared in Ancient Greece where the gnomonics reached high level development.
