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"Tiangong Kaiwu" is a masterpiece of ancient science and technology in our country, which contains a lot of technological technology and natural science knowledge in detail. The physical properties of rivers are described in ancient Chinese by you below.
The water of rivers flows with the trend, which is due to the difference between the height of the terrain. Water has the nature of going down, as if everything in the world follows its inherent principles. From high to low, water flows continuously, which is caused by gravity. The gravity of water makes it converge at the lowest point on the earth, and eventually becomes a river.
And water is fluid, and the intermolecular force is weak, so it can easily change its shape and conform to the twists and turns of the river. In the event of a boulder blocking, the water will pass around and will not stand still. This flow allows rivers to shuttle between mountains and rivers, nourishing the earth.
Furthermore, water has buoyancy. Boats travel on rivers and can float without sinking, supported by the buoyancy of water. Objects placed in water, drain a certain amount of water, and water generates upward buoyancy on objects. When buoyancy equals the gravity of the object, the object can float on the water surface. This principle of buoyancy is crucial in river navigation and is the basis of water transportation.
Water is soluble and can dissolve many substances. In rivers, various minerals and nutrients are contained, which move with the flow of water. This solubility is of great significance to the survival and reproduction of aquatic organisms, and provides the necessary conditions for the continuation of life.
The physical properties of rivers, such as gravity, fluidity, buoyancy, and solubility, are interrelated and together constitute a wonderful scene of rivers, which deduce endless changes on the earth and have a profound impact on human production and life.

The water of rivers has many chemical properties, which are related to many elements, and are connected to the creation of heaven and earth.
Water is pure and soft in nature, and its main components are hydrogen and oxygen, which combine to form H 2O O. This is the fundamental composition of water and the source of many of its characteristics.
River water often contains various minerals, such as calcium, magnesium, potassium, sodium, etc. Calcium makes the water hard, and when appropriate, it is beneficial to human bones and teeth. Magnesium is also involved in various biochemical reactions in the human body, which is crucial for maintaining physiological balance. These minerals are mostly dissolved from the surface and rocks that flow through, so that the water of the river has the ability to nourish all things.
Furthermore, the water also contains dissolved gases, the most common of which are oxygen and carbon dioxide. Oxygen is essential for aquatic organisms, which is needed for their respiration and maintains the ecological balance in the water; carbon dioxide participates in the adjustment of acid-base balance in the water, affecting the pH value of the water body. When carbon dioxide dissolves into the water, it can form carbonic acid, which forms a buffer system with carbonates in the water, making the pH of the water body relatively stable, so that it is suitable for the survival and reproduction of all things.
However, the water of the river is not always pure. If there is industrial pollution, agricultural filth, or life waste dumped in the surrounding area, its chemical properties will change drastically. Industrial wastewater often contains heavy metals, such as lead, mercury, cadmium, etc. These toxins are highly toxic, not only harming aquatic organisms, but also accumulating through the food chain, endangering human health; agricultural runoff carries chemical fertilizers and pesticides, which will also change the nutrient composition of the water body, causing water eutrophication, algae growth, and destroying the harmony of the water ecology.
The chemical properties of river water are not only related to the wonderful creation of nature, maintaining the ecological order, but also vulnerable to human disturbance, resulting in imbalance. Treat it with awe, protect it, and keep it pure, so that the rivers will flow forever and moisten all things.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty. The book has detailed descriptions of many fields, including the application of finless porpoises.
In the field of fishing, the existence of finless porpoises has a certain indicative effect on fishermen. Finless porpoises often swim near fish schools, and fishermen observe their whereabouts, so they can know the location of the fish school, thus improving fishing efficiency. The book records: "When finless porpoises appear, there must be fish schools. Fishermen can find where the fish are and cast their nets to catch them."
In terms of ecological environment indicators, finless porpoises are extremely sensitive to changes in water quality. In places with good water quality, finless porpoises are active and flourishing; if the water quality deteriorates, the number of finless porpoises will decrease or move to other places. It is a "barometer" of the ecological environment of the water. "Tiangong Kaiwu" says: "The number of finless porpoises can test the good and bad water quality. Clean water will make the porpoises prosperous, and water pollution will make the porpoises dilute."
However, "Tiangong Kaiwu" also mentions that the skin, meat, oil, etc. of finless porpoises also had certain uses in the past. Its skin is tough and can be used for tanning, and it can be used for making certain utensils; oil is flammable and can be used for lighting. However, with the changes of the times and the strengthening of ecological protection awareness, the finless porpoise has now become a key protected animal, and it is strictly forbidden to hunt and utilize it to

In "Tiangong Kaiwu", if the method of synthesizing mussels is roughly as follows:
Where mussel pregnant beads, because foreign bodies occasionally enter the shell, stimulated by them, the mussel secretes nacre layers to wrap, accumulating years and months to form beads. To get the synthetic beads of mussels, you first need to choose a good mussel. Choose the one with thick shell, positive shape and strong, this is the basis.
Then, at the right time, the foreign body is implanted into the mussel body by artificial method. The choice of foreign bodies is very important. Take more round and clean things to make the mussel easy to wrap. The place of implantation should be accurate and not hurt its vital parts, and it should be convenient for the mussel body to sense stimulation and start the secretion of nacre.
After implantation, the clam should be properly placed in suitable waters. The water temperature should be moderate, neither too cold to cause the clam body to become stiff, nor too hot to damage its vitality. The water flow should be slow and clear, so that the clam can filter feed freely and absorb nutrients for the formation of pearl quality.
Daily maintenance is also indispensable. Always check the quality of the water, if there is pollution, dispose of it in time. And prevent natural enemies, such as waterbirds, crabs, etc., which may damage the clam and destroy the beads.
After several years, the beads in the clam gradually form. When the beads are full and shiny, they can be picked. When picking pearls, the method should be gentle, not to hurt the pearls, but also to protect the mussels for the next pearl breeding. In this way, the pearls synthesized by mussels are obtained.

The finless porpoise has a saying: "The finless porpoise has a good nature but is not harmful to people, and has no serious harm to the environment."
The finless porpoise is an aquatic spirit. Its body is strong and active between rivers, lakes and seas. Although its body is not as large as that of a whale, its naive appearance often attracts people's love.
In terms of the environment, the finless porpoise is a part of the ecosystem, just like a unique music note in the natural movement. Its survival depends on clean water and abundant fish and shrimp. The reproduction and survival of the finless porpoise is actually a sign of the ecological health of the water. If the finless porpoise can swim freely in the water and play without worry, it shows that the water quality is good and the ecological balance has not been seriously damaged. Therefore, the finless porpoise's safety is also an image of environmental tranquility.
As for the human body, the finless porpoise has neither hurtful habits nor harmful characteristics to the human body. The finless porpoise is gentle by nature, and when it encounters people, it is mostly curious and wait-and-see, and does not mean to attack. And the finless porpoise lives in a vast area of water, which is mostly separated from the area of daily activities of people. There is little conflict between the two, and it has no adverse effect on human health.
Throughout the ages, the finless porpoise has been leisurely in rivers and rivers, adding a touch of agility to the natural picture. It is in harmony with the environment and does not disturb people. It is actually a peaceful existence between heaven and earth. It should be protected with a heart of awe, so that it can enjoy the clear waters forever.