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CHILDREN'S SCIENTIFIC LABORATORY
Ax clock. Children's Science Lab
Directory / Children's Science Lab In a wise Russian folk tale, a cunning soldier managed to cook cabbage soup ... from an ax. However, everything turned out not thanks to the ax ... But the fact that a real sundial can be made from an ax and that such watches were used in the Middle Ages is known for certain. Imagine a large stump with a round horizontal cut, a clear starry night and, of course, an axe. Standing with your back to the North Star, you had to drive the ax blade into the middle of the stump. Then direct the ax to the North Star. Spend under the ax at risk - this is the noon line of hours. Exactly at noon local time, the shadow from the ax handle will coincide with this risk. And if you use the stump as a dial, it really seems like it’s not far from the clock ... Of course, these days a sundial is not really needed. Almost everyone has mechanical ones, and some people have electronic ones - you don’t even need to start them. And yet ... Imagine the following situation: you wandered into the forest, and as if it were a sin, no one has a wristwatch with them. The sun is shining in the sky. If you know how to use it, you can not only determine the time, but also orient yourself on the ground. In addition, isn't it interesting to know how time was determined in ancient times, when there were no wrist or pocket watches at all? Let's see what watches our compatriots used hundreds of years ago.
Before us is a triangular piece of wood with a plumb line, found about a hundred years ago in the Yaroslavl province. In the middle of the triangle is a large round hole. Is this a watch? Yes, imagine a clock. They were used by Russian shepherds at least three centuries ago, and even much earlier. The clock has the shape of an isosceles triangle with an angle at the top of 47°. This angle, of course, is not accidental, 47°:2=23°30'. And this value is well known to everyone who is at least a little familiar with astronomy. + 23°30' - the maximum declination of the Sun during the year. And the minimum is -23°30'. The difference between them will again give the same 47 °. Unfortunately, we do not have the opportunity to give all the astronomical calculations and reasoning that justify the design of the clock. Those of you who are interested will figure it out for yourself using an astronomy textbook and the permanent part of the astronomical calendar. And we will pay attention to something else. We said that simple shepherds used these watches in Rus'. People are not just uneducated - illiterate. And suddenly it turns out that the design of the shepherd's watch is based on rather complex scientific truths, which even today cannot be comprehended without thoughtful hard work. Marvelous? Of course, there is no miracle here. The shepherds did not know astronomy, and yet they were able to make this watch, based on centuries-old practice, on observations that were passed down among the people from generation to generation. Examples of such "smart things" can be found in many museums, and maybe you have them at home too. Be careful with old things. Like old people, they have a lot to say. However, let's return to our triangular clock, or rather, to their image (unfortunately, not a single "live" copy of this clock has survived to this day). On the left side of the triangle, you can see a small through hole (point "but"), and inside the circle opposite this point there is a mark "b" - so straight ab passes through the center of the circle. We have not yet said anything about how we chose the place for the hole on the triangle. а. Of course, this was not unimportant. The rule for finding its center was this: the angle between the line aOb and the base of the triangle is equal to the angle between the noon position of the Sun and the horizon at the equinoxes. Two parallel rows of holes are visible at the base of the triangle: 9 in the bottom and 8 in the top. This is a kind of scale. Now we will see how it works. We will attach a plumb line to the top of the triangle and try to determine the time by this clock. This is done in the following way. We point the clock at the Sun with a hole а- so that on the mark б sunbeam fell. It is clear that in this case the plumb line will take a certain position relative to the holes, depending on the time of day. If the Sun has just risen, the plumb line will pass very close to the edge. А. Further ... however, we will quote what is said in the old magazine, where we found a message about this watch. "As the Sun rises, when observing, it will be necessary to consistently raise the hole а, along with which the position of the plumb line will also change, which will gradually move from left to right; passing along the lower row of points, of which there are nine in total, it will indicate the morning hours of the day: the last point to the right will show 11 am, at noon the plumb line will go to the edge Б, and the hole а reaches the highest position. Then, as the Sun descends, the hole а will begin to fall, and the plumb line will indicate the afternoon hours, passing along the upper row of points, but already from right to left; the first point will mean one in the afternoon, the second 2 o'clock, etc., the last - 8 pm, and at sunset the plumb line will again lie along the edge А". One must think that if we decided to use such watches today, the scale for them could be made more convenient and more accurate than on the old model. How? We'll probably leave that up to you. The most accurate clock readings will be in June, when the Sun is highest above the horizon. If in June the ribБ serves as a time mark for noon, then in other months it will have to be shifted by one point of the lower row to the left (for May and July), by two points (for April and August), etc.: in this way we take into account the decrease in the length of the solar day. And here is another version of the same sundial. The only difference is that they are made of copper and found a little further south - in the Vladimir province (this happened before the revolution). At first glance, these two "chronometers" have nothing in common. Indeed, where is the triangle, where is the round hole, where is the "scale"? If you look closely, it's all there. Instead of a round hole - a round cup on top, with the same small hole for the sunbeam and a mark for the "bunny". The role of the scale is played by two limbs with letters. At the top of the cup is a plumb hook. The rest - most likely "for beauty".
There are suggestions that both watches could also serve as a calendar... The author of the following design of the sundial is known to us. As the journal Izvestia of the Russian Astronomical Society reported, they were "designed and built by the priest of the 17th artillery brigade, D.P. Mudrolyubov." Here they are in the next picture. A vertical metal bracket with a thin wire stretched over it is installed on a fixed base. Perpendicular to the bracket in its middle, an arc is welded in 1/3 of the circle. This whole system can rotate around the vertical axis and in the plane of the bracket. On the arc (it serves as a limb), the hour scale is applied: in the center (the point of intersection of the arc with the bracket) - noon division (12 hours), to the left are the pre-noon hours (11, 10, 9, 8, 7, 6), to the right - afternoon ( 13, 14, 15, etc.). The hourly division price is 1/24 of a circle (15°). Why so - this time it should be clear to you without any special digressions into astronomy.
But how do you get this watch to show the time? Interestingly, first you need to wait ... a clear starry night. The frame with the limb should be fixed in such a position that the wire stretched on the frame was directed to the North Star, and the plumb line suspended from the middle of the wire pointed exactly to the noon division. Now, on a sunny day, the shadow from the wire will indicate the hour of the day on the limb, and if the device is of sufficient size, the accuracy of its readings can be very high. The only remark: the true astronomical noon corresponds to 12 hours only at the equator. In all other cases, it depends on the latitude of the place. (Although, this is not the case - true astronomical noon depends on equations of time.) For example, at the latitude of Moscow, astronomical noon corresponds to approximately 12 hours and 30 minutes. So an appropriate amendment needs to be made. Do not forget also about maternity and seasonal time. Isn't it true that these watches are very similar to the ancient ones with which we began our story? And no wonder: the new is the well-forgotten old.
Look at the drawing. It depicts a sundial used by ancient Roman legionnaires. This stone dial was found in the West German city of Wiesbaden. Along the perimeter of the circle there are inscriptions in Greek denoting the countries of the world, and in the middle there is an intricate figure in the form of a double-sided ax of the ancient Roman lictor (guard). Scientists are still not quite clear how time was counted by these watches. Probably, the watch had some other parts. Time has not kept them... And the last - perhaps the most unexpected in our whole story. Did you know that the most simple and reliable sundial (and a compass at the same time) is ... yourself? Now we will prove it. Suppose that in the morning you went to the forest for berries, you went very far during the day, and now, when it is evening, you are not sure whether you are returning home on the right path. We are sure that you know many ways how to get out of this difficulty. But here's another one. Remember if you saw your shadow when you entered the forest in the morning. (As a rule, a person pays attention to his shadow, so this detail is unlikely to escape you). If before noon your shadow now and then caught your eye, then, now returning home, you should go so that the shadow was again in front: after all, the sun had time to move to the west during the day. And vice versa, if in the morning you did not see your shadow, - in the afternoon, if you want to be in time for dinner, you must go all the time from your shadow. Of course, such an orientation is very approximate, and yet in most cases it helps the lost traveler.
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