The Wooden Ox Makes a Comeback

Over 3100 years ago, the Greeks launched a ten-year war to free Helen from her abductor, the Prince of Troy. In the end, the Greeks built a giant wooden horse, then pretended to abandon their seige. The Trojans wheeled the horse into the city, not realizing their attackers were hidden inside.

（left to right） The Yellow Emperor's "south-pointing chariot," Lu Ban's driverless carriage, and Zhuge Liang's wooden ox-- three of the most important inventions in the history of mechanical engineering in China. （center and right: models by Wang Jian） （right: photo courtesy of Liu Chao-min）

A similar story from Chinese history, from the 3rd century AD, tells how Zhuge Liang, the celebrated strategist from the kingdom of Shu, won a series of battles against the kingdom of Wei thanks to his "wooden ox"-a mechanical beast which had the capacity to walk and featured various mechanisms. It is only in recent years that this fabled object has made its comeback on both sides of the Taiwan Straits.

Determined to wrest control over the central plains of China away from the kingdom of Wei, Zhuge Liang set out from Shu-present-day Sichuan province-on a military expedition to the north. The Wei commander, Sima Yi, refused to engage the Shu forces in battle, however, believing that they would eventually exhaust their supplies and have to return to their distant homeland.

Provisions were already running low when Zhuge Liang summoned all the artisans accompanying the army, over 1000 in number, gathered them together in a hidden valley, and had them make "wooden oxen."

"It is perfect for transporting rations and fodder, but does not need food or water and can run day and night," said the urbane strategist describing his "secret weapon."

When the troops saw it they laughed, and asked: "Where did that come from?" The reply: "The world is filled with things of man's making. I have long observed vehicles throughout the land, and considered the principle by which beasts of burden walk, and thus invented this..."

Fantasy toy

The recent broadcast in Taiwan of the mainland Chinese television series Romance of the Three Kingdoms, has generated renewed interest in stories from the Three Kingdoms period. In the words of National Taiwan University's Professor Liao Hsien- hao, "The Three Kingdoms seem to be alive and well in every field," be it video games, cartoons, advertising, business or politics.

For the older generation, particularly men, the experience of listening to Three Kingdoms stories at Grandpa's knee is fairly universal. Little boys have always been especially fascinated by Zhuge Liang's "wooden ox," that amazing invention which carried the Shu army provisions in the campaign against Wei. "What actually was the wooden ox?" they ask. "Why did it move when patted three times on the backside, but not move when its tongue was turned?"

While most people have puzzled over these questions briefly, there are a few individuals who have made it their quest to find the answers.

According to the leading school of thought on the subject, the wooden ox was no more than the humble wheelbarrow, depicted with a touch of artistic licence by Luo Guanzhong, author of The Romance of the Three Kingdoms. Hence passages such as: "When the wooden oxen were ready it was just as if they were alive, and they were deployed to the full, up hill and down dale" and "The divine troop surged forward, each man wielding banner and sword, fearsome to behold, propelling wooden oxen and speeding like the wind."

Classical histories of that period support the view that the wooden ox was actually a wheelbarrow, as did the late Joseph Need-ham, the British authority on the history of Chinese science and technology, who confirmed this finding through his own research.

The makers of the Three Kingdoms television series originally intended to render the wooden ox as a wheelbarrow, but the director asserted that this would contradict the popular interpretation. It was decided to make a four-legged version instead.

This meant subscribing to an alternative theory, which posits that the wooden ox was indeed a mechanical wonder, able to traverse the rugged terrain of Sichuan. According to this view, there is no other reason for Zhuge Liang's description of its "square abdomen and bent head, with a base of four feet" in his essay on "Making the Wooden Ox."

Also, in the work Political and Strategic Outlook in The Romance of the Three Kingdoms, Luo Guanzhong writes: "A beast of wood can be brought to life." Another military writer, Li Fang, classified the wooden ox as a "device" rather than a "vehicle."

Meeting in Tianjin

There have been various attempts throughout history to resolve the debate by reconstructing the wooden ox. The first to do so successfully was Zu Chongzhi of the Northern and Southern Dynasties period (420-581 AD). According to his biographical record in the official dynastic history, Zu "made an apparatus patterned on Zhuge Liang's wooden ox, propelled by neither wind nor water, and economical in manpower." Unfortunately nothing remains of Zu's creation or its designs.

There were many attempts to recreate the wooden ox during the Qing dynasty, some achieving partial success, but no design records have survived. Mainland China's internationally renowned bridge engineer, Li Guohao, began trying to make a wooden ox when he was still at school, without success, and it was not until 11 years ago that Zhuge Liang's extraordinary invention was finally recreated, by Wang Jian, a lecturer at the Xinjiang College of Engineering in Urumqi. Wang's model used 33 connecting rods, and was designed to simulate the distinctive gait of an ox.

Motivated by a mission to restore national dignity, Wang declares: "The wooden oxen were effectively the world's first successfully applied military robots. They are national treasures of China, and by recreating them I mean to show foreigners the greatness of Chinese science and technology."

The news was reported overseas, and created a considerable stir among the overseas academic community in the States. Friends meeting each other would ask: "Did you hear? They've remade the wooden ox."

In 1986 Wang Jian made his second-generation wooden ox-three full-scale models-and took them to central China for trials on the very tracks where Zhuge Liang transported his army's provisions. Foreign academics and the Japanese media took particular note. In 1991 the Chinese Culture and Movie Center in Taiwan mounted an exhibition on the ancient art and technology of Dunhuang, and included one of Wang's wooden oxen among the exhibits.

In Taiwan, there was also an academic obsessed with ancient mechanical equipment-Professor Yen Hung-sen of National Chengkung University's Department of Mechanical Engineering. During his studies in the US, Yen had found that it was very difficult for Oriental scholars researching Western topics to understand the relevant cultural background, and he resolved thereafter to concentrate his own studies on ancient Chinese technology.

In 1993, when Yen was lecturing in Tianjin, he was introduced to Wang Jian-then working in Beijing-by Tianjin University's Professor Zha Jianzhong. Finding they had a common cause, the three academics decided to cooperate on Zhuge Liang's wooden ox, basing their work on Wang's research.

Sima Yi pays the price for plagiarism

Speaking of his 40-year quest to recreate the wooden ox, Wang Jian comments: "I have loved mechanical toys ever since I was a child. When I learned the story of the wooden ox I began making one out of cardboard and wood. I began drawing designs at middle school, and continued thinking on the subject at university, where I read mechanical engineering. My main sources were "Making the Wooden Ox" from Zhuge Liang's Collected Works, and the documentary records of Zu Chongzhi."

"Making the Wooden Ox" provides detailed external dimensions, such as "Ribs: three feet five inches long," but makes no mention of the mechanism that operates the legs. This is generally explained as the deliberate withholding of a military secret.

Wang Jian, however, believes that there is great significance in the description that is given, even if the details appear trivial. "It includes the external design, measurements, structure and function. Even today, I still don't have a full understanding of this essay."

As an example, Wang refers to The Romance of the Three Kingdoms, which says that when the wooden ox's tongue is turned its legs are rendered immobile. "This is completely true, and provides the finishing touch to the wooden ox," he remarks. According to Wang, one line in Zhuge Liang's "Making the Wooden Ox"-"Where the head joins the neck, the tongue connects to the abdomen"- is explained by the tongue being the mechanism that controls the legs. When Sima Yi ordered his own men to build 2000 wooden oxen for transporting provisions, he had them copy samples captured from Zhuge's army. The Wei side couldn't unravel the mystery of the design, however, and the oxen wouldn't move properly. When the Shu army streamed forward in attack the Wei soldiers abandoned the wooden oxen and fled, handing Zhuge Liang's men a bounty of thousands of piculs of grain.

"This accounts for the subsequent loss to posterity of the wooden ox," notes Wang Jian. "It was such a brilliant invention that no-one else dared make one, and even if they made one they wouldn't be able to control it." Although the episode is not mentioned in the orthodox history of the period, The History of the Three Kingdoms, this is explained by the fact that the book was written during the subsequent Jin dynasty (265-420 AD), under an emperor who was the grandson of Sima Yi, and who would have been displeased by an account of Sima Yi's failure in that battle.

Wooden carriage-driver

Official histories of the period do record Zhuge Liang's making of the wooden ox, but only briefly, and without reference to its alleged wondrous properties.

The following lines can be found in the official biographical record of the Shu ruler: "In the second month of the 9th year, Zhuge Liang set out with his army, using the wooden ox for transport" and "In the tenth year, Zhuge Liang rested his soldiers at Huangsha, encouraging them to farm the land. They finished making the wooden oxen, and Zhuge instructed them in military matters." The biographical record of Zhuge himself, adds little: "He was an ingenious thinker, and devised both the improved repeat-action crossbow and the wooden ox."

The Zizhi Tongjian, an official history spanning many centuries, offers even less comment: "Zhuge Liang encouraged farming, instructed on military matters, made the wooden ox and transported grain for storage at the mouth of Xie Valley."

The Zizhi Tongjian, however, reveals how military strategy often came down to a battle of wits between the rival commanders. Zhuge Liang's army used scaling ladders and battering chariots in their assault on the outnumbered forces of Hao Zhao, but the defenders drove the Shu soldiers back with flaming arrows. Zhuge Liang had the moat filled with lumps of earth to give his men direct access to the city walls, but Hao Zhao had another wall built within the first one. When Zhuge tried to break into the city through tunnels, Hao Zhao countered by sinking fortifications into the ground.

While warfare provided partial impetus for the invention of ingenious new weaponry, "the emergence of the wooden ox was no historical accident," asserts Wang Jian, conveying his enthusiasm for the history of Chinese mechanical science. "It was just one among a series of technological inventions." During the Spring and Autumn period the brilliant craftsman Lu Ban created an unusual carriage for his mother, driven by a wooden figure. Unfortunately, his mother rode away in the carriage and never returned-an incident which is still recalled in proverb.

"This story does at least prove the sophistication of mechanical design in China in that era," notes Wang Jian. Still further back in history, around 4600 years ago, the Yellow Emperor vanquished Chi You in a battle fought in thick fog, thanks to his own direction-finding invention, the "South- pointing Chariot."

Yen Hung-sen, who has made important breakthroughs in the area of variable pitch lead screw mechanics, remarks that China has led the world with many of its mechanical developments: the pulley, gear wheel, roller bearing, and chain drive were all used first in China. In the area of automatic machinery, China was far ahead of the West during the Han dynasty with achievements such as the improved jacquard-type loom (developed by the wife of Chen Baoguang), Zhang Heng's seismograph, and Su Song's water-driven astronomical clock. During the Northern Song dynasty (960-1127 AD) the poet Su Shi wrote the "Song of the Rice- Planting Horse," describing a horse in a field, transplanting shoots by itself. "A real horse can't transplant rice shoots with its hooves," Yen points out. "This definitely refers to a mechanical object." Yen believes the poem is a valuable resource that merits serious research.

Challenging "unconfirmed" mythology

If a mechanical horse for planting rice shoots existed during the Northern Song dynasty, it is not inconceivable that a hand- pushed wooden ox was invented during the Three Kingdoms period.

This is confirmed by Wang Jian's replica wooden ox. "Mind you, I haven't yet recreated it with complete success," Wang says. "There's been a breakthrough, but the results still fall short of Zhuge Liang." Wang explains that there are too many rods in his model, and the structure is overly complex. The walking motion is clumsy, and it cannot carry heavy loads. "My modern methods are no match for the simplicity of Zhuge Liang's design."

As a practical man, Wang Jian relied on basic mechanical principles to overcome difficulties with the design, but for further improvements he has had to turn to system theory analysis, which is where Yen Hung-sen's scientific expertise comes into play. By subjecting Wang's findings to computer analysis, Yen is able to further develop the project in Taiwan, moving towards the production of third- and fourth-generation models.

Says Yen: "It is purely out of personal interest that I study ancient technology. I do it because it has cultural value, not economic or technological value. Many of the inventions of our ancestors are now 'unconfirmed'-that is to say they appear in the historical records, but no examples or designs survive for us to see. It is a great challenge to reconstruct such inventions."

Yen has won financial support for his ideas from Chang Chien-chun, President of Taiwan's Leadwell Machinery Company, and Professor Li Ke-jang of the Junming Foundation, which enables him to carry out research unhampered by other demands. At National Chengkung University, Yen takes on one new graduate student a year, while continuing to pursue the course of his studies.

Stunt performances?

Unlike Wang Jian, students cannot rely on intuition for their work. Study of an ox's walk requires video analysis of every phase in the step motion, such as the height of the hooves, and the resulting tracks, in order to compare the gait of the model with its original.

Wang Jian's model was found to be ill-suited to the demands of moving on rough trails, with the heavy impact of each step jarring the mechanism, and difficulties making it capable of going backwards. The main problem was that on either side, both the fore and hind leg stepped forward in synchrony-unlike a real ox-which made the model prone to tip over. These design flaws can be remedied by altering the dimensions of various connecting rods in the model.

"In making the wooden ox, we have already moved away from trying to replicate the original," says Yen Hung-sen, "and hope to reach a new level using current technology. Beginning with an ambling pace, we want in the future to enable it to run, jump, squat and turn around. Our research will examine how to ensure its functions are as good as possible-raising the hooves to the maximum height, enabling it to be propelled uphill with the minimum of force while also allowing it to automatically run down shallow inclines. It will take a long time just to realize these few objectives."

The improved model that Yen and his students have so far produced is able to remain upright without human support, and can run down an incline on its own without toppling over. In the television version of The Romance of the Three Kingdoms, three pats on the ox's "venerable rump" is enough to set it into motion-an embellishment to the story that originated with the collection Popular Tales from the History of the Three Kingdoms. Wang Jian does not approve: "The wooden ox needed someone to push it in order to move; it didn't walk on its own." Nevertheless, Yen Hung-sen's improved version fits in well with the "imaginative" world of the ancient story, as well as being a fascinating development in its own right.

Chiu Cheng-ping, a student of Yen Hung-sen's at National Chengkung University's Graduate School of Mechanical Engineering, became fascinated with the wooden ox when he read The Romance of the Three Kingdoms at middle school. On seeing a model wooden ox in the professors' lab at university, he chose this as his research topic. Chiu considers it an excellent topic, compared to much else in the field that is too complex and theoretical, and cannot provide practical experience. A topic such as this does not require much funding, and allows for theory and practice to be combined, while also rating highly in terms of challenge and accomplishment.

Was Zhuge Liang an alien?

Yen, last year honored with a lectureship from the Lee Yuan-tseh Foundation for Outstanding Talent, has drawn criticism from others in his academic field for concentrating his efforts on wooden oxen. Their attitude is that it is a waste of time to research something that belongs to the distant past. Yen Hung-sen responds: "If we can't see what is ahead, then why not look back? Who knows what we may discover by re-examining old material?"

Yen points out that today's industrial robots are not particularly well designed. They require enormous quantities of components, comprise both computers and motors, and can easily cost millions of NT dollars, yet all they are capable of is a simple movement. There could be manifold benefits, such as considerably lower costs, and improved reliability, to replacing them with simple equipment similar to the wooden ox, made of rods and levers.

In fact, there is nothing out-dated about the attempt to make a walking machine-it is an area of research that many people and resources are already devoted to in the US, Japan and elsewhere. For example, any space mission involving a landing on Mars will confront the problem of movement on that planet's rugged surface, which is too rocky for a wheeled vehicle like the moon buggy. It will be necessary to create some form of mechanical walking machine similar to the wooden ox, not unlike the mechanically mobile beasts in the Star Wars movies.

Another application for mechanical walking technology is in making improved prosthetic limbs. Lin Wen-hsiang of Sony recalls that when he was a graduate student at Tokyo Industrial University, research was taking place there into walking mechanisms, with the object of helping the physically disabled. At present, many disabled people depend on their wheelchairs to get about, and cannot therefore manage stairs on their own. Some form of walking mechanism, with two or four legs, is required to deal with obstacles such as stairways. Existing robots are motor-powered, and refining the design of the relevant mechanical structure would enable a minimum of motive power to generate the right walking motion.

It may sound simple, but the ideal is still a long way from realization. If a wooden ox able to run, jump and squat can be developed, then the same principle can be used to free the disabled from their wheelchairs, enabling them to get around in much the same way as other people.

Looking back on history, Chiu Cheng-ping chuckles: "In this modern age, it seems like we have a lot of catching up to do in order to understand the wooden ox technology of 17 centuries ago. We end up figuring that Zhuge Liang must have been an alien."

Anticipating the future

Chiu's comment brings to mind Leonardo da Vinci, the 15th century artist and scientist who was also considered an "alien" by some people from later generations.

Zhuge Liang was an expert astronomer and geographer, as well as being a master in military and literary matters. Likewise, Leonardo supplemented his artistic accomplishments with advanced research in the fields of mathematics, optics, mechanics, anatomy, zoology, botany and paleontology. His conceptual designs for various forms of air transport included a precursor to the modern-day helicopter, while he also designed a machine cannon, warship and power-driven armored vehicle. According to The Encyclopedia Americana, Leonardo "far surpassed the era in which he lived, and in many regards anticipated the scientific attitudes and accomplishments of modern culture."

Yen Hung-sen makes an interesting point: "When technology has developed as far as it can, and the way ahead is a big blank, such that we don't know where further progress will lead us, it is perhaps time to start looking back for inspiration."

What we see when we look back may well be the future that was predicted for us by the scientific prophets of yesteryear, such as Leonardo, and Zhuge Liang.

p.32

The third-generation "wooden ox" model, made by Professor Yen Hung-sen and his students at National Chengkung University. Acrylic plastic may lack pedigree, but it makes for convenient monitoring of the mechanism in operation.

p.33

The popularity in Taiwan of the mainland Chinese television series Romance of the Three Kingdoms revived public interest in the "wooden ox." (scene from episode 74 of Romance of the Three Kingdoms, courtesy of Lin Yuan International Co.)

p.35

(left to right) The Yellow Emperor's "south-pointing chariot," Lu Ban's driverless carriage, and Zhuge Liang's wooden ox-three of the most important inventions in the history of mechanical engineering in China. (center and right: models by Wang Jian) (right: photo courtesy of Liu Chao-min)

p.36

(left) No designs exist for the wooden ox, which many academics believe was in fact the wheelbarrow featured in the science history Tian Gong Kai Wu.

(right) The repeat-action crossbow shown in Tian Gong Kai Wu, was developed and improved by Zhuge Liang.

p.37

Europe's earliest mechanical horse. The inventor applied for a patent, but the actual object has never been seen.

p.38

Professor Yen runs an Engineering Design class for senior-year Mechanical Engineering students at National Chengkung University. Students work in groups to make a walking-animal mechanism, which is tested at the end of the course by being required to "ascend to the top of a 15-degree incline within one minute."

p.39

Wheeled vehicles such as the moon buggy would be unsuitable for the rugged or frozen surface of another planet. The technology for mechanical walking could prove useful in future space shots. (photo by Diago Chiu)

p.41

Three partners at National Chengkung University: one on foot, one pushing a wooden ox and one riding a bicycle. Their dream is that in the future everyone can commute to work riding their own energy-efficient, pollution-free wooden oxen.

（left） No designs exist for the wooden ox, which many academics believe was in fact the wheelbarrow featured in the science history Tian Gong Kai Wu.

（right） The repeat-action crossbow shown in Tian Gong Kai Wu, was developed and improved by Zhuge Liang.

Europe's earliest mechanical horse. The inventor applied for a patent, but the actual object has never been seen.

Professor Yen runs an Engineering Design class for senior-year Mechanical Engineering students at National Chengkung University. Students work in groups to make a walking-animal mechanism, which is tested at the end of the course by being required to "ascend to the top of a 15-degree incline within one minute.".

Wheeled vehicles such as the moon buggy would be unsuitable for the rugged or frozen surface of another planet. The technology for mechanical walking could prove useful in future space shots. （photo by Diago Chiu）

Three partners at National Chengkung University: one on foot, one pushing a wooden ox and one riding a bicycle. Their dream is that in the future everyone can commute to work riding their own energy-efficient, pollution-free wooden oxen.