Guangming Qiu was waiting patiently for me outside the National Institute of Metrology (NIM) in Beijing. It was yet another horribly hot and humid July morning. The temperature had climbed above 30 °C by 10 a.m., the air was slightly gritty thanks to dust blowing in from the Mongolian plateau almost 650 km to the north, and passers-by already looked oppressed by the heat. But Qiu – a bright and cheery, white-haired woman, now 75 – seemed unaffected. The last of a team of historians that the NIM set up in 1976 as one of the odd by-products of the Cultural Revolution, Qiu retired 10 years ago but still researches the history of metrology in her own time.

Qiu ushered me into a car and we drove to the NIM’s new laboratory in Changping, an hour or so north-west of Beijing. Its state-of-the-art SI instruments include a “Joule balance” – a device that was designed to evaluate the possibility of replacing the kilogram artefact now at the International Bureau of Weights and Measures (BIPM) outside Paris with an absolute standard. The Joule balance is a novel approach for linking mass with the Planck constant that is not being explored anywhere else but China (and should not be confused with a more common device called a Watt balance that tries to do the same thing).

After a tour of the lab, which pointed to the future of Chinese metrology, we returned to Qiu’s apartment in central Beijing to discuss its past. En route she told me the strange story of how she began to research the history of Chinese weights and measures, which turned out to have as many strange twists and turns as the story of Chinese metrology itself.

Qiu was born in Nanjing in 1936, a time of great upheaval for China as the fledgling republic was still struggling to develop after two millennia of imperial rule had ended some 25 years earlier. In 1937, as the Japanese army marched towards the city spreading murder, rape and horror in its wake, her parents fled to Chongqing in western China, where the Chinese government had temporarily relocated itself. Qiu, a budding artist, studied painting, taught it for a while, but in 1963 was reassigned to a factory in Beijing that had nothing to do with painting: it built measuring equipment for the NIM. Although this was far from what she wanted to do, the move to the NIM was to play a pivotal role in Qiu’s life.

The next twist of fate occurred in 1976, during the waning days of the Cultural Revolution, when the Central Communist Party concocted the seemingly bizarre idea of making a film about how the first emperor of centralized, imperial China, Qin Shi Huang Di (259–210 BC), had unified the country’s system of weights and measures. The country’s first film studio, Changchun, began work on a script and sought to collaborate with the NIM. Institute officials were, however, reluctant – the turmoil of the Cultural Revolution had not entirely subsided and political interpretations of past emperors were dicey matters – and the project faltered and died.

But what the episode did do was to prompt the NIM to establish a group of half a dozen people to research the history of Chinese metrology. During the Cultural Revolution, many researchers had been driven out of the institute and, to help fill the gap, the director asked Qiu to join the new project. This stroke of luck introduced her to the history of Chinese metrology, although she was not formally awarded the title of researcher until the 1990s.

Seeds to SI

Hot sunlight streamed through the windows of Qiu’s tiny apartment, and she got up to draw the curtain. She pulled books off the shelf and opened them to show me pictures of ancient length measures. Initially, Qiu said, she and her co-workers focused on metrology up to the time of Qin Shi Huang Di, but the scope of their research soon covered all Chinese metrology. The group’s work was complex and multidisciplinary, as it involved mastering and piecing together classical texts, ritual practices of ancient courts, cosmology, music and the most recent archaeological discoveries of metrological artefacts. In 1981 the group issued its first publication, an illustrated book entitled Ancient China’s Metrology.

Ancient Chinese emperors thoroughly documented weights and measures, and several texts dating from the second and third centuries BC define the chi, a measure of length, as well as various measures of volume, in terms of a certain number of millet grains. These are more than just a historical curiosity: they are part of the earliest known attempt of any civilization to establish consistent measures tied to natural standards. I asked Qiu if she could relate these ancient Chinese units to their modern SI equivalents.

Qiu left the room and returned with an armful of wooden sticks, each about a foot long, that she had made in the 1990s. Part of the NIM group’s research involved reading classical documents, carrying out their computations and steps, examining existing artefacts and reconstructing traditional practices. Down the length of each stick, Qiu – as per the ancient instructions – had cut a slot into which she had pressed a row of “average” millet seeds of the sort grown in Han-dynasty China. This work, and comparisons with other artefacts, reveal that the early chi was approximately 23 cm, and took about 90–112 seeds to produce.

Although the traditional Chinese measures persisted for thousands of years, they were eventually undone in the wake of the Opium Wars of the early 19th century. These wars were triggered by the impact of British merchants, who had developed a thriving trade for opium grown in India and exported to China. Horrified by the trade, which led to millions of the Chinese becoming addicted to the drug, the Chinese government tried to restrict it. In 1839 Lin Tse-hsu – the new high commissioner for Canton (now Guangzhou) – tried to stop the opium trade altogether, triggering a series of incidents that eventually led to war.

When Lin ordered that all the British be expelled from Macao, a Portuguese trading port over which the Chinese retained power, Britain attacked and easily defeated Chinese soldiers in several port cities, including Canton, and marched inland towards Nanjing. When the Chinese capitulated, the terms of the ceasefire allowed the British to reside and trade in five ports, ceded Hong Kong to Britain, and forced the Chinese government to pay huge sums of money in “reparations” for the war it had caused by its “crime” of resisting British imperialism.

Two other wars followed, opening more cities to British merchants and those of other countries, including France, Russia, Germany and the US, and establishing Macao as a free port, in what amounted to a foreign occupation of key parts of China. Its principal customs and markets were now in foreign hands, and the treaties forced “foreign” measurement units on Chinese merchants in dealings with other countries and diminished the authority of the emperor over weights and measures. Different countries converted Chinese weights and measures into their own systems using different ratios – hated by the Chinese – known as the Custom Ruler and the Custom Balance. Although the foreign weights and measures systems did not penetrate the countryside, they did aggravate the already disorderly local measures.

As Qiu writes in her 2005 book A Concise History of Ancient Chinese Measures and Weights, “The Qing government was neither able to resist the influx of these foreign systems and their applications in domestic daily life, nor did they have the power to unify the measuring and weighing systems in China… The worst part was that the foreigners working in customs took the excuse that the Chinese measuring and weighing systems were too complex and chaotic, and there were no standards to observe; therefore, they had the right to establish regulations on their own, including the exchange rate.”

In addition to reducing China to a semifeudal society, the foreign occupation made weights and measures a huge internal problem. Foreign customs officials distributed their own standards and forced the Chinese to use them. The Qing dynasty, its legitimacy already shaken, suffered another blow when it lost the first Sino-Japanese war of 1894–1895. Struggling to hold the dynasty together, the Empress Dowager Cixi introduced a series of political and economic reforms that included metrology. She ordered China’s ambassador to France to visit the BIPM to seek advice on converting to the metric system, and requested two pairs of metre sticks and kilogram artefacts. These arrived just in time for the end of the Qing dynasty and the creation of the Republic of China in 1912.

The new government was also concerned about the disunity of Chinese weights and measures, and continued contacts with the BIPM, sending its own representatives to the bureau in 1912. The government created a new agency, the Bureau of Measurement, to improve the country’s weights and measures. But moving the metric system into the hearts and minds of the Chinese people proved far harder than the Republicans hoped. In 1929 a law kept the traditional Chinese measures in place for internal use, but put the metric system into play for official transactions.

“The problem was not resistance from the Chinese people,” Zengjian Guan, a historian at Shanghai Jiao Tong University, told me. “The main reason why it took so long to accomplish the transition to the metric system was the social upheaval of China at the time, and the continuous wars and revolutions that the country was experiencing.” The second Sino-Japanese war, which had displaced Qiu’s family and thousands of others too, brought further attempts at conversion to a halt.

After the Second World War, the People’s Liberation Army, led by Mao Zedong, succeeded in driving the Republicans out of mainland China in 1949. The ensuing People’s Republic of China, in addition to rebuilding and modernizing the country, also began to unify the country’s weights and measures system, and began the long process of converting to SI, which was eventually completed when the Act of Measurement was published in 1985.

Switching to the new units was not easy. “But again the Chinese government officials were clever,” Qiu told me. “They told us that the new metric measures were just like the old Chinese measures according to the 1, 2, 3 system: 1 sheng of volume was a litre, 2 jins were a kilo, 3 chis were a metre. When I was a child, I remember thinking, ‘How smart we Chinese are, to have had such accurate measures in ancient times – we were much smarter than the Americans!’ Of course it wasn’t true. But it made it easy to convert.”

The critical point

Qiu’s group at the NIM published numerous books and articles into the 1990s, documenting the history of Chinese weights and measures up to the metric system. But one by one, as members of the NIM’s history of metrology group quit or retired, they were not replaced. “Others in the institute looked down on us, because we were not in the natural sciences and did our research in documents,” recalls Qiu. “Nowadays, people want to work in the lab, [they] like high technology and modern equipment, and are not interested in history.”

Soon she was the only one. When she retired in 1999, nobody replaced her, but that did not stop Qiu from continuing to do research and publish on ancient metrology on her own. Why did she keep going? “I don’t want a luxury life,” she says. “My one desire is to do something the right way. And I don’t like working in big teams.” Being a scholar of ancient Chinese metrology, researching its ingenious artefacts, colourful individuals and compelling tales, was as exciting and rewarding a career as she could possibly imagine.