Sundial | ancient time measuring instrument, not only said imperial power prestige, but also meaning to cherish the time

2022-05-21 0 By

In fact, before watches and pocket watches were invented, sundials were calculators of time, combs that people used to comb time, and where sundials existed, their existence often regulated people’s lives.Now we are still defined by the time of life, but the sundial has long been dragged out of reality, into the depths of history.A sundial is an ancient instrument that measures time using the shadow of the sun.Also known as “sundial”, it is composed of a dial plate and a dial needle.In Chinese sundials, the dial is tilted parallel to the equator.A sundial needle is a metal needle that points to the north and south poles.The shadow of the needle moves with the movement of the sun, and different positions on the dial indicate different moments.The earliest historical record of sundial in China is the short shadow pingyi, or Dipingyi, invented in 574 by Emperor Kaihuang of sui In the Book of Sui · Tianwen Zhi.The clear record of equatorial sundial was first seen in the shadow picture of sundial mentioned in Duxing Magazine by Zeng Minxing in the Southern Song Dynasty.The sundial, as an instrument that uses the projection of sunlight to measure time, is a major invention in the field of astronomical timekeeping by human beings, which has been used for thousands of years.The sundial, also known as “sundial”, is a time-keeping instrument used in ancient China to measure time with the shadow of the sun. Its principle is to use the shadow cast by the sun to determine and divide time.A sundial usually consists of a copper pointer and a stone disk.The sundial needle passes vertically through the center of the disk and acts as a neutral pole for the gnomon. Therefore, the “sundial needle” is also called “table”. The stone disk is called “sundial surface”, which is placed on the stone platform and is high in the south and low in the north, so that the sundial surface is parallel to the equatorial plane.The upper end of the needle points to the north celestial pole, and the lower end points to the south celestial pole.On both sides of the dial surface, 12 large grids were carved, each representing two hours.As early as the Spring and Autumn Period, “watches” for measuring and calculating time had appeared in China.The watch, called Togyu, uses a simple pole that stands upright on the ground to look at the shadow cast by the sun when it points due north at noon, exactly 12 o ‘clock today.In addition, the winter solstice and summer solstice dates can also be determined according to the movement rule and length variation of rod shadow.Although tugui could be used to measure time, the timekeeping device could only take one reading a day, and no other time could be calculated.2 in front of the hall of supreme harmony sundial | need said before the dignity of the royal palace, there are ancient sundial by observing it to determine the time of the timer, is in the heart with a iron needle, needle keep vertical Angle with disc, disc drive Yang position in the sky, through the projection point to the disc iron needles, sundial to be in a higher place.The sundial in front of the Hall of Supreme Harmony in the Ming Dynasty was not a tool to determine the time in daily life, but became a ceremonial object to indicate that the emperor had the right to tell the time.So the Palace of Supreme Harmony in the Forbidden City, dry Qing Palace, need to express the imperial power and dignity of the palace, there are sundials.Sundials spread to western countries and were popular throughout Europe in the 17th century.After the end of The Ming Dynasty, sundials in China and western countries were widely used, and their varieties became more and more.Matteo Ricci’s sundial is in the Library of Xujiahui Cathedral, although no one is watching, the huge sundial still faithfully records the passage of time through the ages.In the Han Dynasty and for a long time afterwards, the sun shadow length measured by the Gnomon was also called “sundial”. It was not until the Yuan and Ming Dynasties that the instrument for measuring the position of celestial bodies and determining time was called “sundial”.After the end of the Ming Dynasty, sundial became popular as the name of a chronometer.The Chinese sundial originated from the Gnomon Sun. When the sun shadow points due north, it is noon, that is, 12 o ‘clock of the local true sun time.As a matter of fact, there is a record of “standing on a watch and missing under a watch” in the Annals of Shiji. It can be seen that time was determined by a watch as far back as the Spring and Autumn Period.But with this method, there is only one chance a day to get a reading, so it can only be used to correct for the speed of missing marks.The speed of dripping changed, resulting in inaccurate measurement, the Han Dynasty began to use sundials to calibrate.When used, the sundial will be placed flat, neutral “positive table” in the heart of the large hole in the sundial, neutral “wandering instrument” in the outer edge of the hole, the positive table and wandering instrument will be illuminated with sunrise and sunset sun position, can calculate the length of the day.Then, the palm leakage personnel to calibrate the flow rate of the clepsydra, adjust the day and night clepsydra.During the Republic of China, a sundial was erected at the south end of the lawn in front of the auditorium, meaning “cherish the time”.During the War of Resistance against Japan, the campus of Tsinghua University was occupied by The Japanese army. The sundial base was still there, but the silver enamel sundial was missing.After the victory of the Anti-Japanese War, Chen Daisun was appointed as the custodian of the school building. He returned to Beiping earlier from Kunming to take over the school property and presided over the restoration of the school building. In the meantime, he made a new stone sundial.Sundials in universities often take the meaning of “cherish time”.In short, sundials measure the time based on the actual position of the sun in the sky, called local solar time.Noon is the exact moment when the sun is at the meridian, casting the shortest shadow directly above the zenith of the sundial.Before people used wind-up clocks, analog clocks, or digital clocks, the sun was the primary means of measuring time.Talk about the history of sundial story, welcome to pay attention to the author | Gong Liuhui