The basis of the sundial is the gnomon. This is a stick, the shadow of which will show us time. The more accurately we orient this stick parallel to the axis of rotation of the Earth (how to do this, see paragraphs 1, 2, 3 below), the more accurate the device will be. As a gnomon, any even stick will fit, similar in size to a shovel from a shovel (you can even use the handle if it is lying around unnecessary).
We find a place where many people and dogs do not run, and by which you often pass. The main thing is that it should be lit by the sun most of the day. To do this, find the south (either navigate on Google Earth, or in the region of 12-13 hours, turn to face the sun) and look for a place on the site with the most free (from roofs, trees, etc.) southern half of the sky.
Next, look at the figure.
Paragraphs 1 and 2 are devoted to finding the exact direction to the North. Yes, you can use a compass for this, but we must remember that the magnetic declination (that is, the deviation of the compass from the real direction to the geographic North) in our country can reach 10, 20 or more degrees. In addition, you can catch a local magnetic anomaly. Therefore, the method for determining the North by the sun is more accurate and reliable.
1. By the time of true noon (the solar climax, it is also mistakenly called the "zenith") we prepare a plumb line (for example, we hang a pebble / piece of iron on a rope and make sure that all this does not hang in the wind) and a horizontal platform on which a shadow from the rope is visible. The methods for calculating the true noon time for your area will be described below.
2. At the time of true noon (previously it would be nice to synchronize the time with the Internet, for example, using the time.is service, or with the ClockSync android application), note the direction of the solar shadow of the plumb line, for example, using several pebbles that we spread along the shadow. This is the exact north – south direction (meridian direction).
3. We calculate the tangent of the angle to the horizontal, under which the gnomon should stand (that is, our stick). To do this, find out the latitude of the place, drive it into the calculator and press tan. For example, if the latitude is 56 degrees, then tan (56) = 1.483.
We multiply this number by, for example, half a meter (50 cm), we get 74 cm. We stick a stick in the ground, in the direction strictly north (we found it in the last paragraph by plumb) from this place we put a pebble 50 cm from the place where the stick is stuck, and tilt the stick so that it passes over the pebble at a height of 74 cm. In Figure 3 (and 3a for the sake of clarity) I showed a plumb line that descends from the gnomon and falls on the meridian line (the length of this plumb line in our example = 74 cm) . Instead of a plumb line, you can "shoot" the eye, but it will not work out so accurately. And in this position, we begin to drive a stick, checking / correcting from time to time so that it passes over our "half-meter" pebble at a given height. As soon as the stick holds tight, we can congratulate ourselves - the most important part of the work is done: we oriented our gnomon parallel to the earth's axis. And by the way, he at the same time with good accuracy points to the North Star (you can check at night, "shoot" the eye along the stick).
4 and 5. The following timer positions are made by timer. It should be noted that even though the picture shows 12 hours for a midday mark, in fact, civil time for it will be different. In order not to think about it, the easiest way is to mark the dial, approaching the gnomon at 13:00, 14:00 and so on, and simply mark the direction of the shadow. And the next day, from morning to noon, mark the remaining hour markers.
The hour markers themselves can be anything: you can drive in plates with numbers, you can lay out stones.
True Noon Time Calculation
I will list exactly what things happen at the time of true noon:
* the sun is exactly in the South (for our northern latitudes),
* horizontal shadows from vertical objects fall exactly to the North,
* the sun is at the highest point of its daily course,
* This is the moment - with good accuracy, the middle between sunrise and sunset on this day.
Each meridian has its own moment of true noon. So, say, in comparison with the center of Moscow, true noon in the east of the city happens about 1 minute earlier, and in the west - a minute later. Here is the annual noon timeline for the center of Moscow (for the time zone UTC + 3, in which Moscow has been constantly located since October 2014):
That is, on the meridian of Moscow you can simply use this chart. Exactly the same form of the graph will turn out in your place, only it needs to be shifted along the vertical axis by the value (D – 37.6) / 15 hours, where D is your geographical longitude. For example, take Perm, its longitude is 56.2 degrees, we substitute it in the formula: (56.2–37.6) / 15 = 1.24 hours = 1 hour 14.5 minutes. That is, in Perm, true noon happens 01h14.5m earlier than in Moscow, and Moscow time, it is necessary to subtract 01h14.5m from the above schedule. For example, for May 22, we get 12h26.5m minus 01h14.5m = 11: 12msk, add 2 hours (the time zone difference between Perm and Moscow), we get 13:12. Remember this time to compare with the following method.
The second method is to find your locality on the weather site, which indicates the time of sunrise and sunset. For example, for the case of Perm, open the Yandex weather site yandex.ru/pogoda/perm and see there Sunrise: 04:37 Sunset: 21:47, we find the arithmetic mean of these two times (04:37 + 21:47) / 2 = 13:12 . Same time as above.
The third method is the use of settlement programs. You can choose a program to taste, I use my Day – night (at the link daybit.ru/v>
1. The above chart for Moscow is a consequence of the so-called Equation of time - the difference between the average solar and true solar time. It should be noted that with the same amplitude as in this graph, the readings of your sundial will change. That is, up to plus or minus a quarter of an hour during the year. However, if you look closely, you can see that in the most interesting summer time for us, the fluctuations are not so great, and fit in plus or minus 5-6 minutes. Sometimes, when they want to get minute accuracy, a schedule of corrections for a year is specially made for a sundial.
From this graph, for example, it can be seen that if you marked your sundial in mid-June, then by mid-September they will be in a hurry for 5 minutes.
2. Why not just use a vertical stick? Why fool around with its slope and its parallel axis of rotation of the Earth? The fact is that a watch made with a vertical stick will sooner or later start to show a noticeably incorrect time. So, a watch made for a vertical stick in June will lie in September for 1 hour in the mornings and evenings. Here is more detailed sundial-ru.livejournal.com/2337.html
3. If you want, you can immediately calculate the dial for your area using, say, the Shadows shadowspro.com program, take the angles from this calculation and immediately measure them on the ground, instead of running around all day and putting marks on the sun's shadow.
In conclusion, as an illustration, I will give one of my watches made "from an ax":
A brief historical excursion
The sundial found particular popularity in the 17th-18th centuries and was used mainly in classical-style gardens - at first in regular, and soon in landscape gardens. For the first time they gained popularity as part of palace ensembles, but mass distribution is associated with the transformation of watches into an independent element of decorative gardens, which, by the way, were performed in a wide variety of styles.
It is often said that Europe is not a suitable place to create a sundial on the site, they say, this is just another attempt to stand out among other summer residents, and to no avail. And they say this because our climate is not suitable for this, since it has many cloudy days. You will be surprised, but all this is another misconception! For example, in England, with its frequent fogs, rare classical gardens do without this decorative element.
About the role of the element in the landscape
Typically, a sundial is located in the center of a flower bed and is the dominant element because it is on a pedestal or other elevation. Also note that the pedestal is an important element of this composition, which is sometimes performed in the form of a column.
A sundial is designed to attract attention, for this reason its size is directly related to the size of a particular site. If the area is small, then it is advisable to install the clock on the path, next to the lawn or a small but bright flower garden. But in a landscape or forest garden it is better to surround them with flowers so that they, invisible from afar, suddenly appear before your eyes when approaching. In addition, in small gardens, sundials are often set in the form of decorative figurines.
Due to the huge variety of materials and shapes used to create the watch, you can get the design taking into account the features of the garden where it was created. So, if the garden is in the avant-garde style, but when performing the sundial, the most insignificant details should be taken into account. Here, watches can become part of a recreation area, a playground or even a gazebo. Moreover, they can effectively decorate a garden pond or fountain.
There is the concept of "living hours." This is another option how to make a sundial do it yourself, but already using flowering living plants, which will serve as material for the formation of the dial and hands.
At the heart of any sundial are two elements:
- a cadran is a flat surface on which the corresponding marking is applied (dial),
- A gnomon is a rod that is attached to this surface.
For the manufacture of watches can be used any material that is resistant to atmospheric factors. It can be stone, cement, iron, wood, plastic, or even gravel. It is desirable that the dial is light (it can be white marble, limestone, etc.): so the shadow from the gnomon will be more noticeable. And the gnomon itself, by the way, can be made of long nails, plastic pins or knitting needles.
Note! The pointer should be slightly longer than the circumference of the dial.
Such watches are able to decorate and revitalize any landscape. Especially if living plants were used for it, not exceeding 50 centimeters in height. For example, calendula flowers bloom at about six in the morning, and close at four in the evening (even if the day turned out to be cloudy).
Good advice on setting a sundial
Now let's talk about the features of the installation process itself. In principle, it is already shown in the image below, but the dial in this case was actually made for solar time, that is, for those regions where noon occurs at exactly twelve zero-zero, in fact, as it should be.
But, unfortunately, in different places noon comes at different times - far from at 12 o’clock. Therefore, if your plan is to see local time on the dial, then it (the dial) will have to be slightly modernized. For this, the numbers on it must be shifted around the axis so that the shortest shadow (namely, it will be observed at noon) moves just along the midday line (north / south).
But the procedure for finding the midday line is already a separate story, but you need to know about it before how to make a sundial do it yourself. So, the compass in this case is unlikely to help, because the magnetic and geographical poles of the planet do not coincide: for St. Petersburg, for example, this is about 8 degrees - that is, the “gap” is on average 30 minutes, which is not so small . The most primitive way is the following: take a plywood sheet, insert a screw or nail into it at a 90-degree angle, then lay the plywood on a horizontal surface and note the movement of the shadow from the pin every fifteen minutes. After that, connecting all the points with a 3-hour line, determine the smallest shadow - it will be that very midday line.
Note! Another practical advice that will help you with the manufacture according to the instructions below: before you start using stone or metal, it is advisable to practice plywood. If you spoil it, then nothing bad will happen, but you will have practical experience.
And the last important point. If we are talking about really good equatorial sundials with a flat frame, then they should have two dials at once - on the lower and upper planes. The first will work from autumn to spring, the second - from spring to autumn. Although, as noted above, for the summer cottage this does not play a special role, since they live there mainly in the summer, therefore, one dial is enough with the head.
Making a sundial: other important recommendations
Before you begin, you should decide on the location. It is advisable to install them on a flower bed or lawn, where sunlight will be available throughout the daylight hours. Typically, the watch can be put both on a flat and on an inclined surface (although in the second version it should be remembered that in order to obtain a shadow of the same length throughout the day, the required angle of inclination must be correctly determined). For its calculation, a special formula is used: 90 degrees are taken and the latitude of the region where your summer cottage is located is taken from them. But in the case of a flat surface, the length of the shadow falling from the gnomon will change throughout the day.
Of course, a shadow of constant length will look more impressive, although this is not important for the simple reason that the length of the shadow from the gnomon can be completely increased mentally.
Video - Sundial in the landscape
After choosing a place, you can start creating a watch face. Its shape, we can immediately make a reservation, may be different, but in most cases, preference is given to the good old classics - a circle or a square - since it is these figures that are easiest to recreate. And if you don’t know how to make a sundial do it yourself and from which, we answer: a variety of materials can be used for this. Among them, we highlight:
- a rock,
- driftwood of unusual shapes,
- perennial conifers
- bright flowering plants, etc.
All this can be used to form time divisions on a frame. But how to divide the area into these divisions? Take a watch (electronic or mechanical - no difference) and, based on their readings, every hour mark the position of the shadow cast by the gnomon during the day.
It is advisable to do this on that day, which is characterized by the greatest duration. Mark each digit with a peg - so between the marks you will get different angular indicators.
Note! If we talk about the gnomon himself, then he is the main structural element, since the shadow cast by him is a kind of clockwise indicating the exact time.
The final step will be the design of the watch. First, think about how you will set the time stamps so that the crops planted next to each digit are provided with everything necessary for normal development and growth. For this, for example, you can indicate even numbers on the outer circle of the cadre, and odd numbers on the inner circle. The diameter of these circles should be approximately 4 meters and 1.5 meters, respectively. It is also important that the plants used for the composition do not grow above 50 centimeters, otherwise the shadow of the gnomon will cover them.
Now - directly to work!
Instructions for the manufacture of sundials
The simplest design of the watch is horizontal, so it can even be done in a pair with your child.
In fact, they can be created even on earth. To do this, draw an even circle, in the center of which stick a stick - it will serve you as a gnomon. Draw a straight line from the center of the circle to the north - it will be noon according to astronomical time. After that, divide the circle into twenty-four equal sectors. Tilt the stick in the north direction at an angle corresponding to the latitude of your particular area. As a result, each of the sectors will correspond to 15 degrees.
Note! Such a sundial will not demonstrate the time that a conventional watch does. After all, solar time, as you know, is not the same as the time of terrestrial time zones.
Now consider how to make a sundial do it yourself, but already portable type. To do this, you need a small cardboard box (always flat), which for effect can be glued with paper to match the color of wood.
If we are talking about a suburban area, then you can use an even round cut of a tree or a flat boulder, and install it at the intersection of garden paths. On the surface, draw a rectangular dial (if the surface is round, then draw a circle). Center the line, cut it to fix the gnomon. The main part of the design is ready!
Теперь сделайте и сам гномон, для чего вам потребуется определить широту местности, где вы обитаете. Для его изготовления можете использовать как пластик, так и плотный картон. Чтобы правильно установить часы, возьмите компас. Направьте острую часть гномона на юг, при этом северное направление будет соответствовать полудню. Вставьте гномон в щель, проклейте стыки клеем.
Для создания делений каждый час делайте отметку местонахождения падающей тени. If you divide the surface into twenty-four parts, then the clock will demonstrate solar time. That's all, good luck with your work!