The history of hourglass

It is said that the hourglass was invented by Alexander in the third century. They sometimes carry it with them, just like the watches people carry today. Speculation was invented as an instrument for sailing at night at the same time as the compass appeared in the 12 century (during the day, sailors can estimate the time according to the height of the sun). The irrefutable discovery dates back to14th century. The earliest hourglass is a written record of Humblot Renzetti's fable, 1338, a suitable government mural. At the same time, the hourglass is mentioned, which appears in the list of ship shops. The earliest existing record is 1345 sales receipt of Thomas Stesham, a clerk on the British ship "Shangri-La George".

Since15th century, they have been widely used in sea, church, industry and cooking. During Magellan's voyage around the world, each of his ships kept the hourglass time of 18. In the paper work on the ship, running the hourglass provides time for the log on the ship.

Before the Jesuits entered Chinese mainland, foreign businessmen and missionaries living in Macau had brought medieval European clocks and watches to Macau. Jesuit Luo Mingjian (Michael Lovgil, 1543 ~ 1607) and Matteo Ricci (1552 ~ 16 10) are in158/kloc respectively. The hourglass, water clock (that is, water sundial) and selfie stick driven by heavy hammer widely used in Europe were introduced into China at the same time. After the hourglass was introduced to China, it was used as a timer in navigation. In the twenty-third year of Qianlong (1758), Huang Zhou wrote "A Brief Introduction to the Kingdom of Ryukyu", saying that when a ship sailed from Fuzhou to Ryukyu, it sailed "60 miles a meter" and was timed by an hourglass. "Every leak is half a meter."

China invented a similar thing called "cleavage" in ancient times, also called cleavage pot.

The earliest records of lost prints can be found in Zhou Li. The oldest unearthed leak is a relic of the Western Han Dynasty, with 3 pieces, which were found in Mancheng, Hebei, Yikezhaomeng, Inner Mongolia and Xingping, Shaanxi respectively. There are two relatively complete leaks handed down from generation to generation, both of which are connected with water. Beijing Museum of Chinese History was built in the third year of Yuan Dynasty (13 16). The one hidden in the Palace Museum in Beijing was made in the Qing Dynasty.

The influential hourglass records in the ancient history of China can be found in the five hourglasses created by Zhan Xiyuan, a great calligrapher in Yuan Dynasty, from 65438 to 0360. Zhan Xiyuan thinks that it seems too simple to let the quicksand flow between two sand buckets. The five-wheel hourglass he created added a mechanical gear set, which was driven by the power of quicksand. Such an hourglass is equipped with a time dial engraved with the time of day, which is equivalent to the clock face of today's clocks. There is a pointer in the center of the time disk, which is driven by the shaft of the last gear. The rotation of the gear makes the pointer indicate the time on the time disk. Zhan Xiyuan also skillfully added a set of mechanical transmission device to the middle wheel, so that the two Xiao Mu images on the five-wheel hourglass can be rotated every hour to beat the drums to tell the time.

We can see that the structure principle of Zhan Xiyuan's five-wheel hourglass chronograph is almost the same as that of modern clocks. However, Zhan Xiyuan was born at an inopportune time. Eight years after the advent of this advanced timer, the Yuan Dynasty perished, and Zhu Yuanzhang, the Ming emperor, was also busy with the power struggle and could not support the development of folk science and technology. This laid the groundwork for China's timer to fall behind the west later.

The convenience of hourglass is that the upper and lower sand barrels can be used upside down. The hourglass also has some shortcomings that are difficult to solve, and the sand is easy to block when flowing. However, the sand used in ancient western hourglasses has a secret recipe to solve this shortcoming: they first boiled marble powder in wine for nine times, skimmed the floating foam, dried it and then used it, so as not to block the hourglass. But the accuracy of hourglass timing is worse than that of drip, so it is not as common as drip. In addition, the hourglass needs a glass container to observe the amount of sand. Most hourglasses in China are made of pottery, so it is impossible to see the amount of sand. This may be one of the reasons why hourglasses are not as popular in China as in western countries.