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Han Dynasty Agriculture

Posted May 8th, 2017 at 08:36 PM by HackneyedScribe
Updated May 21st, 2017 at 08:18 AM by HackneyedScribe

Agricultural had always been stressed by the Chinese literati as the foundation of the state, and under the Han dynasty agricultural production reached its first peak. The founding emperor, Liu Bang, was once a commoner himself. Although Liu the commoner showed no interest in agricultural pursuits, as emperor he soon realized the importance of agronomy for state building. It is without question that his heirs also adopted similar viewpoints. Canals were dug, fields were irrigated, and incentives were given for families to bring new lands under cultivation. Only by adopting improved farming methods would the Han Empire be able to achieve a registered population of nearly 60 million, with an even higher actual population.

Soil Differentiation: Just as a battlefield commander must be familiar with the terrain, a farmer must be familiar with his land. The types of crops best suited to the types of soil is aptly studied and documented, although this was already in practice seven centuries prior to the Han dynasty as witnessed in the 5th century BC text Tribute of Yu. They also studied how to adapt soil to best suit particular crops, which will be addressed later.

Pre-treatment of Seed: Seed was pre-treated with all kinds of fertilizer, which includes cooked animal bones and silkworm debris. The fertilizer is mixed with aconite, perhaps acting as a pesticide. Pre-treated seed offers superior germination upon planting. However, as this method requires many types of resources, pre-treatment of seed was perhaps only practiced by agricultural estates or well-to-do farmers. Such an advanced method wouldn't be heard from again until the 20th century!

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Left is precision seeding by hand shown in Han dynasty stone art. Right is a reconstruction of a Han seed drill. Bottom is a pictorial representation of the alternating fields method

Precision Seeding: From ancient times, farmers planted seeds by broadcasting. That is, they scattered seeds by hand. Such a method causes a list of problems. Many of the seeds would never germinate due to a combination of elements and pests. Those that did grow would compete against neighboring shoots for nutrients. Hence the famous farmer's adage: “One for the pigeon, one for the crow, one for the harrow, and one to grow”. Yet by at least the Zhou dynasty an alternative practice was introduced. This was the practice of planting in rows with the seeds placed into holes dispersed by regulated intervals, aka precision seeding. Master Lu’s Spring and Autumn Manual of the 3th century BC described
if the crops are grown in rows they will mature rapidly because they will not interfere with each other’s growth. The horizontal rows must be well drawn, the vertical rows made with skill, for if the lines are straight the wind will pass gently through.”
Also, by insuring that each seed was planted deeply, the natural danger of the elements would be mostly avoided. Thus the chance of germination per seed increased, along with the speed and quality of growth. Weeding became much easier as farmers could now weed by walking in between the rows of crops. Such methods allowed a common seed return ratio of 66:1000 for millet, the most common grain of the Han Empire. As for grain yield, an average farmer’s output is bumped up to around 3 hu per mu (526 liters or 984 lbs per acre) per year. On the other hand, a typical agricultural estate, which would have the best land with the best tools, could produce on average 13 hu per mu (2281 liters or 4265 lbs per acre). Best of all, precision seeding can be practiced at no cost to the farmer, so even the poorest farmers could enjoy its application.

Multiple-tube seed drill: Although precision seeding allowed less seed to be planted per acre while still giving a higher yield, a laborer needed more time to plant the seeds as opposed to using the broadcasting method. Hence the multiple-tube seed drill was invented to decrease the time needed for precision seeding. By using the multiple-tube seed drill, the farmer was able to till the land while sowing seeds simultaneously. By the Han dynasty wooden-tube seed drills were replaced with ones made completely out of iron tubes. Seed drills of this era came with either one, two, or three tubes. Naturally, the one-tube seed drill can plant one row of seeds at a time, the two tube seed drill can plant two rows simultaneously, while the three tubed seed drill can plant three. Such devices were said to automatically plant seeds 3 inches beneath the soil, and land tilled by the seed drill looked like it had been gone over by a small plough. The advantages offered by the seed drill can be read in a 250AD text, which described the introduction of the seed drill to the Empire’s westernmost region of Tun-huang:
In Tun-huang they were not familiar with the seed drill, so that they wasted both seed and the labour of men and oxen in return for poor harvests. Huang-Fu Lung taught them to make seed-drills, and this reduced their labour by half while increasing their yields by five-tenths. –Cheng Lun
Even the contemporary complaints against the less efficient seed drills are still fairly impressive for the time:
Emperor Wu appointed Chao Kuo the chief commandant for grain; he taught the people farming. According to his method, three plows are pulled together by one ox. One person leads the ox, handles the plows, and hauls the seeder-all taken care of by himself. In one day he plants 100 mu. Down to today the three metropolitan districts still rely upon the benefits of his method]. Now the cultivating plow in the commandery of Liao-tung has a beam four ch-ih long that hinders it in turning about. Two oxen are used; two persons lead the oxen, and one handles the plow. One sows the seed, and two haul the seeder. In all, they use two oxen and six persons; in one day they can only plant 25 mu. Such is the disparity. [CHHW46:11a-b]
The official is actually complaining that a certain two oxen plough from the Han frontier could only go through 25 mu of land a day! Using the mu of Chao Cuo's period, 25 mu accounts to 1.19 acres. For ancient times this really wasn't that bad at all for a two oxen plough. In comparison the Roman one oxen plough could till one iugerum (0.625 acres) per day, and this doesn't take into account the time necessary for seeding. Nevertheless, we can be sure that the one oxen plough and seed drill of the three metropolitan districts does a better job than the Liaodong two oxen plough and seed drill. The former plough was more prevalent as well because, according to the Han historian Sima Qian, the three metropolitan districts boasted 40% of the empire's population and 60% of empire's wealth. Whereas Liaodong was only a northeastern frontier commandery.

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Han stone pictorial of a hybrid horse and oxen plough

Horse harness (chest): The horse harness existed in China by at least the 4th century BC. By placing the yoke across the horses’ chest, it allowed horses to plough much more efficiently from alternative harness systems. This allowed poorer farmers to adopt horses for beasts of burden as substitutes to oxen, because horses were much cheaper to maintain. Although an ox is stronger than a horse, a horse has the advantage of greater endurance. As such horses may be the preferred animal over oxen in areas of light soil. Another advantage for raising horses is that it allows the family to avoid conscription. The following is a Han era discussion showing what horses could be used for during times of peace:
Before the expeditions against the Barbarians of the North and South,…. farmers employed horses for ploughing or packing, and everyone among the people could ride in saddle or chariot. In fact they considered at the time the advisability of restricting the use of horses to the fields [as opposed to battle].”-Discourse on Salt and Iron
Alternating fields: The widespread practice of precision seeding allowed certain doors to be opened for the Han agricultural family. The Lushi Zhunjiu written during the Qin dynasty described the method of ploughing followed by distributing seeds along the ridges created by the furrows. This system was replaced by the Alternating fields system, introduced by Chao Cuo during the reign of emperor Wudi. This involved planting the seeds in the furrows rather than the ridges. When weeding, soil would naturally fall from the ridges into the furrows, allowing roots to be grounded deeper into the earth. The ridges protected the seeds from wind and also conserved water more efficiently. Also, each year the position of the furrows and ridges were switched. Thus the system not only allowed the ridges to protect the seeds from the elements, but also allowed the soil to maintain its fertility. Thus Chao Cuo introduced a system equivalent to biennial fallowing but without the necessity of having half the land lie fallow. A pictorial explanation of this method is depicted in the first picture above. After Chao Cuo was able to confirm his speculations by experimenting with such methods in his own field, instructions were sent out to diffuse the knowledge starting from the capital to the three metropolitan districts and then to the frontier regions. What's more, Chao Cuo's way of proving his new method is very similar to what we know today as the scientific method: Hypothesis, Conduct Experimentation, and Communicate Results. It appears that the alternating fields method became widespread and widely praised in a short amount of time.
He[Wudi] made Chao Kuo the chief commandant for grain. Kuo knew how to make tai-t'ien, or "alternating land," in which one mu had three furrows whose position was exchanged yearly. Hence it was named alternating land. This was an old method, Hou chi being the first to arrange fields with furrows.....Kuo experimented by having the guards at the detached palaces till the side lots of the palaces. A check of their harvest showed that they all obtained over a hu per mu more than adjoining fields. He ordered that the soldiers teach their relatives to cultivate the government lands of the three metropolitan districts. He also taught the border commanderies and of Chu-yen city. Later he also taught the border commanderies and of Chu-yen city. Later he also taught the people of the border cities, of Ho-tung and Hung-nung commanderies, and the three metropolitan districts, and of the territory under the jusrisdiction of the grand minister of ceremonies; all found the tai-t'ien system advantageous. They expended less labor and obtained more grain - Han Shu
Due to this, yields were claimed to be increased by 1 hu per mou, and even an increase of 2 hu per mou when under efficient management. Indirect advantages of the alternating fields method is the introduction of new agricultural tools, including the long handled hoe for weeding and an improved oxen-driven plough of two shares. However, this system demands much energy for poor peasant families who cannot afford oxen for ploughing. Ploughing fields is still possible with only human labor, although to do so is exhausting. However, given that a field is ploughed, utilizing the system of alternating fields requires no additional resources.

Multiple human powered plough: Yet how could everyday peasants, whose families were unlikely to own more than 5 acres of farmland, be able to take advantage of the Alternating Fields system? Plus, to plough speedily after raining is essential, as this practice best allows the soil to preserve moisture. To plough too late after rain means that the moisture in the soil would evaporate. The average family had few to no work animals, slowing down the ploughing process. This problem was solved by a prefect of Ping-Tu, who employed Chao Cuo, the very advisor who came up with the Alternating Fields method. Cuo taught the people to help each other in pulling ploughs together [something still practiced today], so that his alternating fields method could be used even by the poorest farmers. Under his instructions, with many people thirty mu (1.43 acres) of land could be tilled in a day. With few people thirteen mu (0.62 acres) could be tilled in a day. It is heavily implied in the passage that what Mr. Cuo did was call adjacent farming neighbors to plough each other’s land together as a team: “Help me plough my land today, and I’ll help you plough your land tomorrow”. This would be much more efficient than having each man ploughing only his own land.

Heavy moldboard iron plough: Whether a plough is human or animal powered, its design is essential for efficient work. Although wooden ploughs with iron blades existed from the Zhou dynasty, Han ploughs included the addition of an iron moldboard which turns the soil to either side as the ploughshare cuts forward, and prevents the ploughshare from being clogged with soil. Pre-existing ploughshares only had an iron blade, but by the Han dynasty completely iron ploughs sprung into existence. The plough was sophisticated enough to allow the depth of the furrow to be determined, thanks to the addition of an adjustable strut. The moldboard's curved design gives minimum drag when pushed against the soil.
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Han dynasty moldboard and ploughshare at upper right. Bottom left is a rake

Pit cultivation: Yet what could a family do if they had so few land that not even plough was justified? To address this problem for the extremely poor families came the birth of pit cultivation. The method requires only a little amount of low quality land, and it could also be practiced on steep slopes where implementation of conventional farming methods is impossible. Pit cultivation may have existed since the 3rd century BC, as much of it resembles methods described in the Lushi chunqiu. Only by the late Western Han do we find detailed descriptions of pit cultivation in Fan Shengzhi’s manual of agriculture, which survived in fragments. The manual describes how the land is divided into grids, with one 9.2 by 4.8 inch pit in each grid. Twenty millet seeds, provided with a copious amount of fertilizer, are planted in each pit. Although pit cultivation requires much labor, it does not require much heavy labor. This allows a farming family to utilize even children to work the fields, so what was previously a liability for rural families is now an asset. The system allows good ventilation and sunlight for the crops, while the pits provided protection from wind and moisture loss. Chi Ssu-Hsieh added his own commentary to Fan’s agricultural manual by saying:
Liu Ren Zhi, the governor of Western Yen-Zhou, an experienced and truthful man, told me that when he was in Luoyang he took a piece of land 70 paces on his property and experimented with pit cultivation, and he harvested 36 hu of millet. If this was true then 1 mu would have yielded over 100 piculs. Such a method would be most appropriate for households with little land.
Although the claim is without doubt unrealistically high, an experiment done in Honan and Hubei in 1958 showed that the yield was much higher than conventional methods. Despite such obvious advantages for a farmer with little land and resources, pit cultivation are mostly adopted rather the government, gentlemen-farmers, and large landowners. The abundant use of top-grade fertilizer is simply not available to poorer farmers. Also, the heavy amount of human labor can only be provided by the government who had armies of convicts (or tenant farmers for large landowners) residing within imperial fields.

Pot Irrigation: Once a field is ploughed, the next concern is regarding the best way to conserve water within the soil. By the Han dynasty a method was born in which clay water pots were buried into the soil. The water would seep through the pots and into the roots of a plant through osmosis. Best of all, the rate of osmosis is dependent on just how much water the plant needs. Pot irrigation is undoubtedly a very important practice in places where water supply is few.

Fire tilling/water weeding: The agricultural methods of the south developed along different lines from those of the north. The lower population density of the south meant that farmers could have land to spare. Fire tilling resembles earlier slash and burn techniques through the burning of weeds in a fallowed field and planting rice seeds after the field is flooded. Weeds were allowed to grow until a certain height, which by then the water was raised to drown the weeds. The dead weeds would decompose to feed the rice plants. The control of water is critical for this system. In a cold environment, the flow of water must be limited in order to give it enough time to gather heat, whereas in a hot environment the flow of water was sped up for cooling. The control of water was accomplished by manipulating access channels in the irrigation system. A great advantage of water irrigation is that it allows the practice of horticulture. Fish were raised in the rice paddies and need not be fed as they would eat the parasites living within the water. As such they provided farmers with another source of food at no cost.

Crop rotation/Double cropping: Different types of plants require differing types of nutrients from the earth. This means planting alternating types of crops in the same piece of land would be able to prevent soil erosion by a great deal. The Han dynasty practiced a 3-field crop rotation. During winter wheat was planted, which is heavily dependent on nitrate. Once the wheat was reaped, millet was planted afterwards. Although millet is also a nitrate hungry crop, it does not require as much as wheat. Once the millet was reaped, soy beans would be sown in its place. These legumes produces nitrate of its own, which rejuvenates the soil of its depleted nitrate content. It is possible that the Han dynasty produced the modern method of four-crop rotation once emperor Wudi received alfalfa seeds from the Western Regions (alfalfa is to be planted after legumes). If the production of grain became unprofitable a farmer could reap a millet field and then burn the leftover stalks in order to provide fertilizer for mulberry trees. Mulberry trees can be used in the production of silkworms. A farmer must be cautious, however, for burning stalks may lead to soil erosion in windy weather. Although the wealthy would have no trouble adopting crop rotation practices, crop rotations for average Han farmers would be sporadic but not to the extent that it was rarely practiced. In every four years there would be five harvests, meaning in one of these years the land was double cropped.

: In addition to crop rotation, transplantation was practiced for the growing of vegetables. The work of Fan mentions how melons, scallions, and beans were planted together. The downside to this is that planting different crops within the same space would make use of the seed drill difficult. One major advantage for both crop rotation and transplantation is pest control. Pests tend to be specialized in their diet, so the repeated substitution of one plant species for another means that pest populations would not have the opportunity to rise out of control. The practice of transplantation increases the space between similar plants, which reduces the main food source of pests specialized to consume only one particular plant species.

Water lifting devices: Ploughing and seeding is only the beginning. Seeds must be well watered to germinate, but to do so by hand is labour intensive. Wang Chong during 80AD might have described the earliest use of the chain pump when he mentioned ‘water-men’ directing water to the city of Luoyang. By 186 AD, the earliest direct mention of square-pallet chain pumps were mentioned where Pi Lan built chain pumps and siphons to direct water into the city, “thus saving the expense incurred by the common people”. The same passage mentioned norias [waterwheels] that brought water into the palace. The existence of similar water lifting devices must have existed at least 1000 years before this, for ancient water pipes were commonly found in even pre-Shang China. The use of chain pumps were not simply restricted to urban cities, as chain pumps served as a handy tool for irrigation. Without the chain pump, farmers would have to resort to raising water by hand or counterweight buckets.

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Han dynasty pottery figurines of winnowing fan machinery, operated by crank handles

Rotary winnowing fan: Once a crop is harvested, a farmer’s work is not yet done. Many crops are not edible in their harvested form, and must be processed prior to consumption. The practice of winnowing was usually done by hand in order to separate the chaff from the grain. This involves simply throwing the grain into the air with a basket, hoping that the wind will pick up the lighter chaff while the heavier grain falls to the ground. The Han dynasty invented a rotary winnowing fan. Instead of throwing the mixture into the air, it was poured within the winnowing machine while the “wind” was artificially produced by a crank handle. The Han pottery figurines also show one of the earliest evidence for crank handles.

Crank and connecting rod for querns:
The earliest evidence for the crank and connecting rod dates to a Western Han stone pictorial, called long(砻). The pictorial depicts a person milling by hand, which was a labor intensive process. Putting a crank and connecting rod onto a millstone would not only reduce the time needed to finish milling, but also require only a fraction of the effort. These devices use reciprocal motion (pushing and pulling motion) to drive rotary (circular) motion rather than vice versa, much like what drives the wheels on a steam locomotive.

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Image cropped from "International Symposium on History of Machines and Mechanisms". Two Western Han stone reliefs showing manually operated longs were unearthed in Chonggang (重岗) and Sihong(泗洪), Jiangsu province.
The most important thing about this machinery is its cheapness, so that even a peasant could have the resources to build one. What's more, this technology may be what led to the invention of the water-powered blast furnace, except for the latter it was the rotary motion that acted as the catalyst for the reciprocal motion. Refer to the end of this essay for further details.

Hydraulically powered and animal powered trip hammer
s: This device was used for pounding, as a way to decorticate grain. The Xin Lun, written in 20 AD, claimed that just the human operated trip hammer could be 10 times more efficient than the pestle and mortar. The Xin Lun also mentioned trip hammers operated by various beasts of burden as well as those that were hydraulically powered by a waterwheel. Thus, considering the technological maturity of the trip hammer by 20AD, being powered by human, animal, or even water, the first trip hammers must have been existent long before this.
Fu Hsi invented the pestle and mortar, which is so useful, and later on it was cleverly improved in such a way that the whole weight of the body could be used for treading on the tilt-hammer (tui), thus increasing the efficiency ten times. Afterwards the power of animals—donkeys, mules, oxen, and horses—was applied by means of machinery, and water-power too used for pounding, so that the benefit was increased a hundredfold. -New Discourses of Huan Tuan (20 AD)
The technology spread rapidly. In the Book of Jin, a certain Shi Chong 石崇in 296 AD described his ten qing (121 acre) estate as having watermills located in over thirty sites (水碓三十余区).

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Song dynasty representation of water-powered trip hammers, already available by the mid-Han dynasty

There is currently debate about whether the "water power" quoted above was describing drop spoons, horizontal waterwheels, or vertical waterwheels as seen in the picture above. Even if we exclude the Han era Mingqi pottery (located in the Hong Kong Museum) depicting a series of trip hammers powered by a vertical waterwheel, the answer should be obvious. The same quote from Huan Tuan described the use of "donkeys, mules, oxen, and horses" for powering trip hammers, which meant the Han artificers already knew how to convert horizontal rotary motion of animals to power trip hammers. To do this, such a horizontal rotary motion needs to be combined with a vertical rotary motion. It is not a mental leap to simply re-locate that "horizontal" rotary motion to a river, creating a horizontal waterwheel. But if they do that, it is also not a mental leap to simplify the machine altogether by getting rid of the horizontal waterwheel, so that the vertical rotary gearing becomes the new, more efficient vertical waterwheel. In other words, the quote is most likely talking about a vertical waterwheel, or both the vertical or horizontal waterwheels. Having the technology for animal powered trip hammers means they also have the technology for trip hammers powered by horizontal and vertical waterwheels. A drop spoon, on the other hand, is another type of design altogether. The following picture shows my explanation much more clearly:

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Depiction showing how the rotary motion of animal-driven machinery could easily be converted into waterwheel driven machinery

Water trapping: Once the fields are harvested and the grain processed, a farmer’s work is not done. With the onset of winter, snow must be rolled to trap moisture within the earth. Snow that was rolled also kills insect eggs that would have otherwise survived through the winter. By summer the soil was pulverized, as pulverized soil holds water better. Water could also be rerouted through particular irrigation channels based on different times of the year, as a way to control water temperature.


Other Han technologies that directly or indirectly affected Han agriculture and Han agricultural families include:

1) The foot operated drawloom and the spindle wheel, for weaving. The standard family upkeep would be to have the men farm outside, while the women stay inside the home to weave. Clothing could make up a substantial amount of the family's yearly income, especially when sericulture was involved. Wealthier families would naturally be able to afford more expensive and better machinery, albeit poor families may form weaving hubs to pool their resources together.

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Above is a Han model drawloom found in the tomb of Wan Dinu. Bottom middle show the movements of the drawloom, and bottom right is a photo of the excavation itself. Bottom left is a spindle wheel

Previously it was thought that early drawlooms would not be able to weave complicated patterns. The model drawlooms found in the tomb of Wan Dinu, however, showed that Han drawlooms were not just foot operated, but sophisticated enough to design complicated patterns.

2) The wheelbarrow
, for ease of transporting heavy goods. Han era wheelbarrows tend to have their wheels located in the front, which was better suited for light loads. Later Chinese wheelbarrows moved the wheel to the center, which was better suited for heavier loads.
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Han era pictorial showing a wheelbarrow

3) Water Powered Furnaces: Ancient China already utilized the Blast Furnace and the Cupola furnace, allowing iron to become widely available to the common people. It was during the time of the Han that water power was first used to power furnaces. The question is whether these furnaces were powered by a horizontal or vertical waterwheel, as no pictorial evidence from the period remains.
In the seventh year of the Chien-Wu reign period (31 AD) Tu Shih was posted to be Prefect of Nanyang. He was a generous man and his policies were peaceful; he destroyed evil-doers and established the dignity (of his office). Good at planning, he loved the common people and wished to save their labor. He invented a water-power reciprocator for the casting of (iron) agricultural implements. Those who smelted and cast already had the push-bellows to blow up their charcoal fires, and now they were instructed to use the rushing of the water to operate it...Thus the people got great benefit for little labor. They found the 'water(-powered) bellows' convenient and adopted it widely - Book of Later Han
Unfortunately the earliest pictorial depictions only appeared more than 1000 years later. By this time furnaces could be powered by both the horizontal waterwheel, or by a vertical waterwheel (not depicted but clearly described). A single vertical waterwheel was described as capable of powering multiple furnaces much like how it was capable of operating multiple trip hammers at once (see above for water powered trip hammers).

Wang Zheng of 1313 AD gave the most detailed description of the two versions of water powered furnaces:

Horizontal waterwheel:

According to modern study (+1313!), leather bag bellows were used in olden times, but now they always use wooden fan (bellows). The design is as follows. A place beside a rushing torrent is selected, and a vertical shaft is set up in a framework with two horizontal wheels so that the lower one is rotated by the force of the water. The upper one is connected by a driving-belt to a (smaller) wheel in front of it, which bears an eccentric lug (lit. oscillating rod). Then all as one, following the turning (of the driving wheel), the connecting-rod attached to the eccentric lug pushes and pulls the rocking roller, the levers to left and right of which assure the transmission of the motion to the piston-rod. Thus this is pushed back and forth, operating the furnace bellows far more quickly than would be possible with man-power.

Vertical waterwheel:

Another method is also used. At the end of the wooden (piston-)rod, about 3 ft long, which comes out from the front of the bellows, there is set up right a curved piece of wood shaped like the crescent of the new moon, and (all) this is suspended from above by a rope like those of a swing. Then in front of the bellows there are strong bamboo (springs) connected with it by ropes; this is what controls the motion of the fan of the bellows. Then in accordance with the turning of the (vertical) water-wheel, the lug fixed on the driving-shaft automatically presses upon and pushes the curved board (attached to the piston-rod), which correspondingly moves back (lit. inwards). When the lug has finally come down, the bamboo (springs) act on the bellows and restore it to its original position. In like manner, using one main drive it is possible to actuate several bellows (by lugs on the shaft), on the same principle as the water trip hammers This is also very convenient and quick...

So whether the Han used the vertical or horizontal waterwheel is open to question. The below shows the two possibilities:

Click the image to open in full size.
Bottom shows a hypothetical reproduction of a Han furnace using a vertical waterwheel, and the right shows a furnace using a horizontal waterwheel, depicted in the NongShu. Note that Han bellows used leather bags, not wooden fan bellows. Also, the horizontal waterwheel used a belt drive to operate a upward facing crank (oscillating rod), converting its rotary motion to lateral motion

The Han certainly had the technology for the vertical waterwheel, as it is not that different a design from the animal/water powered trip hammers that were available to them. But they also had the technology for utilizing horizontal waterwheels for furnaces as well, as can be seen from archaeology. An excavated site shows that as early as the Western Han, the Chinese knew how to convert horizontal rotary (circular) motion to the reciprocal (pushing forward and backward) motion needed to operate their push-bellows. Donald Wagner has the following to say about the Western Han Wafangzhuang foundry site:
Near the remains of several cupola furnaces, is a circular pit, 2.6 m deep and about 6 m in diameter. Whatever mechanism was used here, its purpose was to convert rotary motion to reciprocal motion, and a similar arrangement could have been used for water power. It is fairly easy to imagine a version of the mechanism for a water powered bellows shown in the Nongshu of 1313, with its horizontal wheel, being used here. “ -Donald Wagner
In other words, all they had to do was place the 'rotary motion' into a river, and they would be able to transform a muscle powered bellow into a water powered bellow. If the excavated machinery operated anything like the later horizontal waterwheel driven bellows, then it would be the earliest example of not only the belt drive, but also the water-powered crank and connecting rod. Also, refer to the Han dynasty hand operated crank and connecting rod mechanism for milling (except for bellows, it is the rotary motion that functions as the catalyst for the reciprocal motion).

4) Borehole Drilling, used for extracting salt from deep within the earth. This method was useful for lowering the price of salt in places far from the ocean. Even the natural gases found deep within the earth was transported above by a series of pipes. These natural gases were used for heating the salt evaporation pans. A lot of heat was certainly needed, as salt evaporation pans could weigh close to a ton and must be constantly replaced as the heat they must endure from underground gas was astronomical. By the Song dynasty, bamboo cables were used, allowing the drilling to go as far as 1000 meters deep. During the 1860s, the same method was used in California to drill for petroleum, called "Kicking Her Down". According to Needham, the Chinese who were brought to California for building railroads, may have also introduced the method of deep borehole drilling to the Californians.
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