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Clean Power Yangsui

Published on December 4th, 2014 | by Glenn Meyers

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The Oldest Solar Device in the World

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December 4th, 2014 by  

This story on the oldest solar device is part of an overall series of articles by author John Perlin that provides entertaining and readable information on the history of solar energy. They were originally published on Green Building Elements. For those who want to know more, read his book! It is well worth the time investment.

Special thanks to author John Perlin for this contribution about what is believed to be the world’s oldest solar device – a solar ignitor, or yang-sui. The material comes from Perlin’s recently published book, Let It Shine: The 6000-Year Story of Solar Energy.

By John Perlin

During the sixth century BCE, Confucius wrote about the common use of curved mirrors shaped from shiny metal to concentrate the rays of the sun for making fire. These became known as yang­­-suis ­­– translating to solar ignitors, or burning mirrors.

Yangsui

According to the great philosopher, upon waking up the eldest son would attach a solar ignitor to his belt as he dressed for the day. It was his duty to focus the solar rays onto kindling to start the family’s cooking fire.

According to another early text, the Zhouli, which describes rituals dating far back into Chinese antiquity, “The Directors of the Sun Fire have the duty of transferring with burning mirrors the brilliant flames of the sun to torches for sacrifice.”

Although scholars found over the years many ancient texts discussing solar ignitors, the discovery of an extant yang sui eluded them for centuries. Quite recently came the Eureka moment. Digging up a tomb that dated to about three thousand years ago, a team of archaeologists found in the hand of a skeleton a bowl-shaped metal object. While the inner side could have passed for a wok, the exterior trough had a handle in its center. That’s what caught the eye of the two archaeologist in charge of the dig, Lu Demming and Zhai Keyong. They immediately brought the relic back to the local museum and ordered its specialists to make a mold from the original and then cast a copy in bronze.

Yangsui30

After polishing its curved surface to a high degree of reflectance, the inquisitive archaeologists focused sunlight onto a piece of tinder just as the eldest son would have done so many years past, and in seconds the combustible material burst into flames. “This verified without a doubt that the purpose of the artifact is to make fire,” Lu and Zhai later wrote, assured of having found the oldest solar device in the history of humanity.

yangsui 3

Now that the world could see what a real yang-sui looked like, museums retrospectively identified 20 more previously unclassified objects as solar ignitors. Multiple molds for turning out yang suis later found at a Bronze Age foundry in Shanxi province, close to the first find, suggest a mass market once existed for them. In fact, yang suis were probably as ubiquitous in early China as are matches and lighters today. The yang sui “should be regarded as one of the great inventions of ancient Chinese history,” remarked its discoverers, impressed by the ability of their forefathers to figure out the complex optics for such optimal performance so early in time.

About the Author: John Perlin is author of four books: “A Golden Thread: 2500 Years of Solar Architecture and Technology;” “A Forest Journey: Wood and Civilization;” “From Space to Earth: The Story of Solar Electricity;” and his latest book, “Let It Shine: The 6000-Year Story of Solar Energy.” Harvard University Press Chose “A Forest Journey” as one of its “One-Hundred Great Books” published by the press, as well as a “Classic in Science and World History.” The Geographic Society and the Sierra Club chose the book as their “Publication of the Year.” “Power of the Sun” and “Sunrise” are two documentaries for which I did the screenplays. “Power of the Sun” was done in collaboration with two Nobel Laureates at University of California, Santa Barbara, where I am now a member of the Department of Physics. 

Photos via Let It Shine: The 6000-Year Story of Solar Energy

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About the Author

is a writer, producer, and director. Meyers is editor and site director of Green Building Elements, a contributor to CleanTechnica, and founder of Green Streets MediaTrain, a communications connection and eLearning hub. As an independent producer, he's been involved in the development, production and distribution of television and distance learning programs for both the education industry and corporate sector. He also is an avid gardener and loves sustainable innovation.


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  • john

    Talking about reflected light or more correctly refracted light I have seen bush fires started by the Australian habit of throwing the stubby out of the window of the car.
    The broken glass refracts light and starts a fire.
    Off track with the article I know but just a side comment

  • Victor Provenzano

    Around 2200 years ago, Archimedes invented a similar device as a weapon of war to light Roman ships on fire at a distance. Rows of polished bronze shields were arrayed against the Roman navy in 212 B.C.

    • Larmion

      The problem is that Archimedes’ mirror has never been corroborated by archaeological evidence and present day reconstructions failed to light anything on fire.

  • Paul Bear

    Chlorophyll? Awesome tech article.

    • Larmion

      Bacteriochlorophyll (as found in purple bacteria) actually predates chlorophyll by a fairly long time. It’s used in anoxygenic photosynthesis, a process that produces sulfur compounds rather than oxygen as a byproduct.

  • timpster

    I wonder what they did for light three thousand years ago — holes in the ceiling? Fire would have been too smoky, maybe they use…. skylights?

    • Offgridman

      Oiled paper or the inner membranes of animal hides for the common people, and thin sheets of mica for the more well off were used in windows before the intensive production of glass became common. These weren’t something that you could look out through, but they did let in light while keeping out the cold.

      • timpster

        wow very interesting!

        • Offgridman

          Should have added that fire was also used for light, but not as big torches or firepits as you may be thinking.
          Their are remains back to almost paleolithic times (pre bronze age) of various types of lamps that burned oil or fat with a plant fiber or animal hair wick. Some of the originals just being a roughly formed stone or clay bowl with various modifications and improvements through the millenia to the current kerosene lamp.

          • Bob_Wallace

            Oil lamps are pretty low tech. A bit of clay, a bit of fiber or hair for the wick.

          • Offgridman

            Of course they are compared to what is currently available for sources of light in modern society. Makes it all that much more something to be changed that there is still a sizeable percentage of the world’s population that still count on fire for their source of light at night.
            The question that I attempted to answer was what was used for a source of light in the homes of 3 thousand years ago, thank you for providing a pictorial example, it too might be considered to be low tech for some of the residents of that time period.

          • Bob_Wallace

            I’ve seen plenty of these simple oil lamps in use in India and Nepal. The next step up is a metal lamp with the wick sticking out the top, but no glass chimney.

      • Larmion

        Mica doesn’t keep out the cold – its thermal performance is extremely poor. It was also very rarely used even by the rich because of its rarity in most of the ancient world and the lack of large, solid slices. Oh, and it’s extremely fragile.

        Glass was more widely used than you suggest even in ancient times. Glassblowing was already done on a large scale in pre-Roman times (though the glass was always slightly tinted; truly clear glass is a fairly recent innovation). In medieval times, stained glass was the to-go choice for the .01%.

        However, the vast majority of windows were simply holes in the wall. They were left open when weather allowed for it and shut with a wooden plank or some tatchwork. Even the rich chose fairly small windows to keep out the cold.

        Oiled paper is far more recent than glass. It saw some early use in Japan and China, but only took off when it was used by colonists in the US (very recent indeed in historical terms).

        • Offgridman

          Yes Europe did see a serious decline in the quality of social and construction standards after the decline of the Roman empire.
          However with this being about ancient China what I was referring to were archeological finds from the Ukraine across eurasia to the Hindus Valley from that same time period that are thought to have influenced Chinese development by the original Aryan culture.
          Yes mica is a poor insulator just as is single pane glass but it does keep out the wind and let in the light, and the couple of remains found have some theorizing that putting the pieces together piecemeal led to the development of the stained glass windows.
          Yes also oiled paper came a bit later in China and Japan in the pre-Christian millenia, but there have been numerous examples found of the use of the inner membranes of Reindeer, elk, and back to paleolithic times from mammoth hides to make a light admitting cover for window’s or as scrims. This was most likely the precursor to the idea of using oiled textiles or paper to cover window’s.
          Not trying to say that everyone had these, or even that they were in common use, when I said common people it more referred to rich merchants or traders that would have heard of these ideas on journeys or through trade.
          But not all of our ancient ancestors lived as primitive a lifestyle as you portray happening in medieval times. Quite a bit of that can be associated with people thinking that they needed to suffer on this earth to earn a reward from their god. Which social deception was not prevalent in pre Christian times and there is a lot of archeological evidence showing that we tried to enjoy life and live in as high a standard as possible.

          • Larmion

            Yes, animal hides were used where available and affordable – no argument there. It’s the mica and oiled paper that I disagree with: oiled paper is a fairly recent innovation and mica is too rare to be worthy of mention.

            The average medieval society certainly wasn’t as primitive as commonly thought, but windows certainly were small holes covered with wooden shutters or something similar for the vast majority of the population – that’s clear from both the archaeological record and the buildings still standing in Europe from medieval times.

            I also disagree with the link between Christianity and poverty. For a start, the whole glorification of suffering is a fairly recent phenomenon. The medieval Church, especially in the west, was a lot more pragmatic than given credit for. It was closely tied into wordly affairs (monasteries and cathedrals were places of commerce, learning and worldly power) and thus had every interest in a vibrant, prosperous society. Faith was something malleable, something that integrated seamlessly into the needs and desires of the faithful. And God? God was a very much a guy you could do deals with. If you bribed him, he’d reward you regardless of your occasional sins – it’s amazing how tolerant Church leaders were of what happened behind closed doors.

            Only after the reformation did the idea of intense study of scripture and the associated emphasis on suffering, poverty and earning rewards made an unwelcome comeback.

          • Offgridman

            Perhaps it was a mistake to bring up the god thing, it is perhaps more personal opinion that the christian religion has had as many detrimental affects on society as positive. As for the connection with wealth as you said yourself it didn’t cause any reduction, but did encourage the display of it to be behind closed doors. As to the purchasing of forgiveness that was one of the detrimental aspects that allowed the church to gain a stronger control over society and its wealth.
            The question by the original commentor was what was done in ancient times to bring light into a home other than fire, so a few of the options were mentioned. As to the use of any of these options being to minor to mention, you are free to have that opinion, but that doesn’t mean that they weren’t used. The archeological evidence shows that not all homes were dark cave like dwellings lit by only fire for more than five thousand years, so that was explained. So whether it was wood, animal, or plant products, or in rare cases minerals, man has been ingenious enough to have windows in his homes that let in air and light and in some cases block one or the other for many millenia.

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