World Water Day: A review of the “water artifacts” invented in ancient China

On January 18, 1993, at the 47th United Nations General Assembly, March 22 of each year was designated as World Water Day, calling on the public to strengthen water resource protection. In ancient my country, when science and technology were far less developed than today, in order to better use water and prevent water, our ancestors gave full play to the wisdom of the Chinese nation and invented a large number of instruments that amazed later generations. Today, let's take stock of these "water artifacts"!

01 Dredging Artifact - Mud Driving and River Diversion Dragon

The rivers in northern my country have been full of silt since ancient times. The pre-Qin poetry collection "Book of Songs·Xiaoya" says: "Carrying clear water and turbid water", which reflects that our ancestors noticed the difference between clear water and turbid water very early. If the water carries too much silt, it will cause big trouble - causing the downstream river channel to silt up, and then the river will burst, causing terrible floods. Therefore, clearing silt and dredging rivers have become important tasks of water conservancy projects in successive dynasties in my country.

The mud-driving river dragon is a hydraulic dredging device invented by the Qing Dynasty. The device is about 5.3 meters long, 1.3 meters wide at the front, and 0.6 meters high. The structure diagram of the mud-driving river dragon drawn by the Qing Dynasty detailed the various parts and their functions of the device. One of its biggest highlights is that it has a large mouth for water intake and a small mouth for water discharge.

Figure 1: Structure diagram of the mud-driving and river-diverting dragon ( drawn by a Qing dynasty scholar)

The design of the mud-driving river dragon with a large inlet and a small outlet determines that its outlet flow rate is much higher than the inlet flow rate , which greatly improves the sand-carrying capacity of the water flow [1]. When using mud-driving river dragons, they are generally arranged in a row of 10, and the downstream scouring distance of each row of river dragons is about 16 meters, and the daily scouring depth is also "several feet". Using a boat to carry a mud-driving river dragon and sail downstream of the river can achieve good dredging results.

02 " Multifunctional " artifact - small mouth pointed bottom bottle

This peculiar pottery is called "small-mouthed pointed-bottomed bottle" in archaeology. It is one of the most representative artifacts in the middle reaches of the Yellow River during the Yangshao and Miaodigou culture periods of the Neolithic Age. It was "popular" intermittently for about 1,500 years. Small mouth, pointed bottom, two ears... What is the purpose of such a "peculiar" shape? The academic community has given a variety of explanations based on different scientific principles.

Figure 2: A small-mouthed pointed-bottomed vase unearthed from the Banpo site, collected by the National Archaeological Museum of China (copyright image of the gallery; reprinting may lead to copyright disputes)

Some scholars believe that according to the principle of floating centroid mechanics, the body of a small-mouthed pointed-bottomed bottle is easy to sink in water, and it automatically stands up when full of water, so it is speculated that it should be a water pump (i.e. used to draw water). Other scholars believe that the special "pointed bottom" shape of the small-mouthed pointed-bottomed bottle can be embedded in the ground or a special fixed base, so it may be used to store hot water, similar to a modern thermos bottle . Some scholars believe that the small mouth is conducive to sealing and the pointed bottom is conducive to sedimentation, which are both excellent conditions for brewing wine, so it is speculated that it is a wine brewing vessel [2]. Of course, some scholars also speculate that the small-mouthed pointed-bottomed bottle was a ritual vessel used for sacrifices at that time. Regardless of what the small-mouthed pointed-bottomed bottle was used for, it contains so many scientific principles. For the Chinese ancestors thousands of years ago, they had already won.

03 Flow measurement artifact - Li Bingshi

The measurement of river flow was very important to the production of ancient people. In the field of water conservancy engineering, discharge refers to the volume of liquid passing through a certain water section of a pipe, open channel or other channel per unit time, measured in cubic meters per second . As a measured data, discharge is an important information reflecting water conditions, and is also a basic data reflecting water resources and changes in water volume in rivers, lakes, reservoirs and other water bodies. [3]

The average flow velocity on the water-passing section (the flow velocity is determined by the slope , roughness , etc.) multiplied by the water-passing section area can get the flow value, and the ancient Chinese ancestors seemed to have known this relationship for a long time. For example, the Li Bing Stone Man in Dujiangyan is a stone statue-shaped water-flow measuring ruler, whose shoulders and feet are water-flow measuring scales. "Shui Jing Zhu·Volume 33" records that Li Bing made three stone men standing in the water: the feet of the stone men do not show the water surface during low water, and the shoulders of the stone men do not submerge in the water during high water. Dujiangyan has two relatively stable conditions, one is the water inlet section , and the other is the riverbed slope . In this way, the water shortage in the irrigation area can be inferred through the reading of the water ruler , which in turn reflects that the "Li Bing Stone Man" does not simply reflect the water level, but also reflects the amount of flow below the water level . Therefore, it is well deserved to say that the Li Bing Stone Man is a flow measurement artifact.

Figure 3: A replica of the stone statue of Li Bing from the Eastern Han Dynasty, housed in the Sichuan Museum in Chengdu, China (copyright image from the gallery; reprinting may lead to copyright disputes)

04 Mechanical water-lifting device - keel waterwheel

How did ancient people first carry out agricultural irrigation? In the literature of the pre-Qin period, there is a record of "holding a steamer to draw water". The steamer is a cooking utensil used for steaming food in ancient China. It is shaped like a basin or a pot, with a large mouth. It is often used in conjunction with a "li" through a hollow grate to form a "yan". The water vapor in the li can heat the food in the steamer until it is cooked, but the steamer is rarely used alone. Imagine holding a large basin to draw water for irrigation, and you will feel that it is not an easy job to draw water manually.

Although water-powered and wind-powered water-lifting machines were gradually invented later, human-powered water-lifting machines themselves were also constantly developing. For example, the human-powered (or animal-powered) wheel-powered water-lifting machine, the keel waterwheel, first appeared in the Eastern Han Dynasty. This is the folk name for it, because it has an extra-long water-scraping runway connected by wooden tips, like a keel frame. The keel waterwheel uses human or animal power to rotate the wheel axle to lift water. Among the keel waterwheels that use human power to rotate the wheel axle, small keel waterwheels are hand-cranked , also known as "paddle wheels"; large keel waterwheels are pedal-operated , also known as "pedal wheels" [4].

In my country's plain areas, especially under conditions of close distance and water lifting height controlled at 1m-2m, keel water wheels are very suitable for agricultural irrigation. They have played an important role since the Tang and Song Dynasties. Until the 1950s, keel water wheels could still be seen in my country's rural areas.

Figure 4: Hand-cranked keel waterwheel model, collected by China Agricultural Museum (Photographed by Zhai Guoqing; reprinting may cause copyright disputes)

Figure 5: Pedal-type keel waterwheel model, collection of China Agricultural Museum (Photographed by Zhai Guoqing; reprinting may cause copyright disputes)

summary

In fact, the above is just the tip of the iceberg. In the splendid history of China, there are countless "water artifacts" invented by ancient ancestors with their wisdom, such as the "rolling broom" used for emergency blocking or bank protection projects, the "mixing river dragon" used for dredging rivers like the mud-driving and river-diverting dragon, and the "level" used for water conservancy project measurement, etc. It is precisely because of these great inventions that for thousands of years, we have been able to reasonably utilize water resources to contribute to civilization and step by step usher in the dawn of modern times.

References:

[1] Lu Jiaxi, History of Science and Technology in China. Water Conservancy, Science Press, 2002.

[2] Yun Zerong, “Re-exploring the Basic Functions of Small-mouthed Pointed-bottomed Bottles”, Journal of Cultural Relics Appraisal and Appreciation, No. 13, 2013.

【3】Encyclopedia of China, 3rd edition, online version

[4] Jin Feng, “China’s Traditional Large-Scale Irrigation Farm Implement: Waterwheel”, Agricultural Archaeology, No. 3, 2013.

author:

Member of the BoxCat Chinese Science Writers Association, winner of the third prize in the article category of the 2017 "Top Ten New Science Makers" competition

Zhai Guoqing, member of the Chinese Science Writers Association, 2016 "New Science Maker"

Reviewer: Song, Yuan and Ming Dynasty Associate Professor, Institute of History of Science and Cultural Heritage, University of Science and Technology Beijing

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.