Day and night - day away

One, two, three - it took some time until we said these three short words. How much exactly?

Something like one second. Compared to an hour, this is not much. Time is very relative. Sometimes it seems that we feel it physiologically - how agonizingly the waiting time drags on! But it is worth doing some exciting business - and time will pass imperceptibly, rapidly, as if it will be reduced a thousand times.

But these are emotional feelings. In fact, time is a physical concept, independent of our feelings and moods, and, like any physical quantity, has its own special units of measurement.

Second, minute, hour, day - all these are definite quantities, "portions" of constantly running time, which has only one direction - forward. And not a second ago.

Everything that exists in nature is embodied in space and time. And people noticed this a long time ago, since they learned to think. They could not help but pay attention to the rhythms of nature around them: the heartbeat, the alternation of inhalation and exhalation, the change of day and night, a periodic change in the lunar phases, seasonal changes in nature associated with the change of seasons. Rhythms could be long and short, they, like a pendulum, helped people "listen" to the silent but continuous flow of time. Nature itself suggested this method - the diurnal movement of the Sun.

Now, looking at the clock, we rarely think of the Sun. We don’t think that the hands (or numbers on the electronic clock display) are inextricably linked with the Sun, and that it changed its usual course, we would have to redo all the clockwork anew.

At first, people simply divided the day into day and night. The length of the day is a value given by nature itself. "Day and night - day away" - this proverb completely satisfied the everyday idea of ​​time in ancient times. Only four hundred years ago it became known that a day is nothing more than a period of the Earth's revolution around its axis. In order to be able to mark shorter periods of time, day and night were divided into 12 parts - hours, and at first their duration was unequal - after all, in summer the days were longer than night, in winter - on the contrary. In total, the day was 24 hours - two dozen. It is known that the number 1 2 was then especially respected due to divisibility by 2, 3, 4 and 6, it was widely used in mathematical calculations and in trading operations. By virtue of tradition, the ancient counting of time has been preserved for over four thousand years.

The simplest clock of antiquity was a gnomon - a tall pillar standing in an open place. In the morning and evening, when the sun was still low, the shadow from the pillar stretched across the entire square. In the middle of the day, it shortened, and in countries close to the equator, on some days of the year it disappeared altogether if the Sun was at its zenith at noon.

On the Champ de Mars in Ancient Rome there was a majestic stone pillar - the obelisk of Sezostris 34 meters high, taken by Emperor Augustus from Egypt as a war trophy. The obelisk "Cleopatra's Needle" located in Cairo enjoyed no less fame. There were sundials and more complex devices.

It is possible that people in different countries invented sundials independently of each other. The Indian Brahmins carried with them a special faceted wand - Jacob's staff, into the drilled recesses of which a small rod was inserted - a shadow indicator marking the time of day. Wall clocks, such as vertical clocks, were widely used on the octagonal Tower of the Winds in Athens, clock on the ruins of a Greek temple in Boeotia.

The vertical sundial still exists today.So, in Moscow they can be seen on the building of the Historical and Archival Institute, as well as on one of the wings of the Novodevichy Convent. No less common horizontal clocks survived in the park of the village of Kolomenskoye, are demonstrated at the Astronomical Site of the Moscow Planetarium.

But the sundial is convenient where clear weather prevails. And they work only during daylight hours. Therefore, even in ancient times, water clocks - clepsydras - were invented. They were vessels, from which water poured out in a thin constant stream, and were much more complex in design, an example of which can be the famous Ktesibia clock, which has not only technical but also artistic value. Clepsydras were used during court and government sessions, where each speaker was given a strictly defined time: if he got too carried away, he was reminded: "Your time is up!"

Clepsydra have even been used in medicine. So, the ancient Greek physician Herophilus used them to check the pulse of patients suffering from fever.

The hourglass, which was widespread in the Middle Ages, looked more simple. Specially treated sand was placed in glass vessels located one above the other, where it was slowly poured from one to another. The hourglass has retained its practical value only in medicine.

In China, a fire clock of this design was used: from special varieties of wood, ground into powder together with incense, dough was prepared, from which sticks were rolled, giving them a various shape, for example, a spiral shape. They smoldered slowly over many months. At certain intervals, metal balls were attached to the rod, which, when the rod burned out, fell into a porcelain vase, producing a loud ringing - a fiery alarm clock.

There were other ways of measuring time - people could not do without it. One cannot but agree with the opinion of the historian of ancient technology G. Diels:

The beginning of scientific thinking, which brought man out of the animal state, is associated with the measurement of time.

B. A. Maksimachev