Ancient seismology and Chinese polymath Zhang Heng

Detail of linocut 'Zhang Heng' by Ele Willoughby, 2023 on 9" x 12" washi paper. 

This is a linocut print about the ancient Chinese Han Dynasty polymath and statesman Zhang Heng (78-139) who invented a device (a seismoscope, like a simplified seismometer which does not make a record of earth motions) to detect distant earthquakes and indicate their direction, 2000 years ago! I have shown him in blue with a reconstruction of his seismoscope, and a schematic of how it might have worked in bronze, as well as horizontal earthquake surface waves, and Rayleigh waves in particular, in pale pink.

A career civil servant in Nanyang, Zhang Heng (sometimes formerly written Chang Heng) was also an astronomer, mathematician, seismologist, hydraulic engineer, inventor, geographer, cartographer, ethnographer, artist, poet, philosopher, politician, and literary scholar. He was a bit of a controversial figure politically, sparing over calendar reform and with rivals amongst the palace eunuchs. But both his poetry and famous inventions are still remembered. He also improved the Chinese approximation for π and made an extensive star catalog. He understood that the Sun and Moon are spherical, and that the Moon merely reflects the light of the Sun. He also explained the nature of solar and lunar eclipses. He invented the world's first water-powered armillary sphere for astronomical observation; improved the inflow water clock by adding another tank; and, as celebrated here, he invented the world's first seismoscope, which recorded distant earthquakes and their origin (in terms of 8 cardinal directions).

China is a seismically active place, and while the cause of earthquakes remained misunderstood, in 132 Zhang Heng was able to design a device to detect seismicity from distant sources. It was named "earthquake weathervane" (hòufēng dìdòngyí 候風地動儀), and it could roughly indicate where the earthquake came from. According to the Book of Later Han (compiled by Fan Ye in the 5th century), his bronze urn-shaped device, with a swinging pendulum inside, was able to detect the direction of an earthquake hundreds of miles/kilometers away. The outside of the device was described as having 8 dragons with balls in their mouths and 8 open-mouthed frogs around the base which could catch fallen balls (and indicate direction to the source). If there was an earthquake the dragon facing its location would drop a ball into the mouth of a frog below. The Book of Later Han claims that the device was triggered by an event, which was too subtle for people to feel but that the west-facing dragon drop its ball. Officials doubted the device worked as intended, but several days later a messenger arrived from the west and reported that an earthquake had occurred in Longxi (modern Gansu Province). So, the court acknowledged it in fact worked.

Unfortunately, no ancient Chinese seismoscopes have survived and details of the mechanism are sparse. The description of the detected earthquake was written much later. So, we cannot be certain about how it worked precisely; some even doubt that it did. Later Chinese inventors were not able to reconstruct the device. However, a series of modern seismologists have put forward a series of reconstructions. There are several ways a pendulum could trigger a ball to fall. Some of the questions include: was it a regular pendulum? Was it an inverted pendulum? How was its motion transferred to the appropriate dragon and not to any other dragons? How it avoid "false positives" due to other sources of shaking? 

As a geophysicist myself, I find the contemporary reconstructions of Feng Rui and others pretty convincing, so that's what I have illustrated. These scientist argue that the device would have detected horizontal motions due to surface waves which would only be due to earthquakes, and would not be set off by vertical motions (which can be caused by earthquakes or nearby shaking, say, due to people). So they built a reconstruction which they argue is consistent with the description, but detects Rayleigh surface waves. They argue by adding a second ball inside the device, it could have avoided having two opposing dragons triggered. In their model, illustrated in my print, when there is an incoming wave, for instance, from the west, the pendulum would move from west to east. They made a hollow inside, so the pendulum would drop a ball, falling on the west side as it moves off-centre. The ball follows one of 8 radiating tracks, then pushes a lever connected to the dragon mouth and the west-side ball - and no others - would fall. This would correctly identify the direction.

They also make arguments explaining that some reconstructions are not the right style of urn or dragon, arguing that Han Dynasty dragons would have been much simpler than the fancy Ming Dynasty ones shown on some reconstructions. So my illustration tries to respect the archeology of ancient Han artifacts, as well as a mechanism which apparently avoids the pitfalls of previous reconstructions. I also included a waveform, which seismologists will recognize as a horizontal Rayleigh wave (detected by a modern seismograph).

Sources

Zhang Heng, wikipedia, accessed January 2023

Feng, Rui and Yu Yan-xiang, Zhang Heng's Seismometer and Long earthquake in AD 134, Acta Seismologica Sinica, 19, 704-719 (2006)

Feng, R., Wu, Y. Research on history of Chinese seismology. Earthq Sci 23, 243-257 (2010). https://doi.org/10.1007/s11589-010-0720-z

Hong-Sen Yan, Kuo-Hung Hsiao, Reconstruction design of the lost seismoscope of ancient China, Mechanism and Machine Theory, Volume 42, Issue 12, 2007, Pages 1601-1617, ISSN 0094-114X, https://doi.org/10.1016/j.mechmachtheory.2007.01.003.

Zhang Heng Seismoscope, Atlas Obscura 

Jamie Rigg, The ancient earthquake detector that puzzled modern historians, engaged, September 28, 2018

Andrew Robinson, The world's first seismometer used a toad to catch an earthquake, New Scientist, 30 November 2016

Hertha Ayrton, Mathematician, Physicst, Engineer and Inventor

 

Hertha Ayrton, linocut, 9.25" x 12.5" by Ele Willoughby, 2021.

This is my linocut portrait of British engineer, mathematician, physicist & inventor Hertha Ayrton (1854-1923). She is remembered for her research on the electric arc lamp, on ripple marks in sand & water, and her inventions including of mathematical line dividers which allowed artists, architects & engineers to enlarge or diminish drawings. I’ve shown her with a diagram of the dividers from her 1st of 26 patents, one of her diagrams about the origin & growth of ripple marks & one of her diagrams of an electric arc lamp (a subject on which she literally wrote the textbook).⁠
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Born Phoebe Sarah Marks in Portsea, Hampshire, she was the third of eight children of a Polish Jewish immigrant watchmaker father & seamstress mother. After her father’s death when she was 7 in 1851, the family was left penniless and her mother returned to work as a seamstress. Sarah, as she was then known, had to care for her younger siblings. When she was 9, her maternal aunt Marion Hartog, who ran a school in north-west London with her husband Alphonse Hartog, invited her to join their household and attend their school. Though a hardship to her family, her mother recognized her potential and supported the move to London and the opportunities for her daughter. Her cousins introduced her to math and science. In her family, she was known as a fiery and occassionally crude character. By 16, she was living independantly, employed as a governess.

Her friend Ottilie Blind nicknamed her Hertha after the poem by Algernon Swinburne. They coached each other to prepare for the Cambridge entrance exam. Blind introduced Hertha to her mentor feminist, suffragette and founder of Girton College (the first residential college for women in England), Barbara Bodichon, after who she would later name her daughter. Her extended family and the suffrage community helped her get a higher education; author George Eliot* (a friend whom she met through Bodichon) wrote in support her application to Girton College, at Cambridge. She did not win a scholarship and would not have been able to afford tuition but she was supported with loans and donations from the suffrage community. While there studying math, she founded the fire brigade, led the choral society, and with fellow student and mathematician Charlotte Scott, formed a mathematics club. She also developed her first patented invention, the line divider and developed and built a sphygmomanometer (for measuring a person's pulse) while still an undergraduate. She passed the famous Mathematical Tripos in 1880, but Cambridge wouldn’t grant women degrees. She was able to take and pass a University of London equivalency exam, and they granted her a BSc in 1881.⁠
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She earned an income teaching embroidery and math. She ran a club for working girls and looked after her invalid sister. By 1884 she had her first patent for a line divider; she also sought a US patent for it in 1885. Lady Goldsmid and Barbara Bodichon provided the funding she needed to seek these patents. The invention was well-received and got good reviews in the scientific press. She presented a paper on her invention to the Physical Society in 1885 and the device was manufactured in six sizes by a scientific instrument maker. Supporters encouraged her to become an entreprenneur and inventor but she wanted to pursue a scientific career.

She began evening classes on electricity with Professor Will Ayrton, trailblazer in engineering education at Finsbury Technical College. She was one of 3 women among 121 students. He was a widower with a young daughter, and a supporter of women's education and fight for voting rights. They married in 1885 and began collaborating on physics experiments and she was able to work from the lab in their home. A year later, they had a daughter, Barbara Bidochon Ayrton. From 1888 she taught practical and domestic electricity to women. Between this, domestic chores and raising her young daughter she had little time for research.

When her mentor Bodichon died in 1891, she left Ayrton enough money to support her mother and hire a housekeeper. Will supported her research but was also careful to not always collaborate with her, so that her work would be recognized as independant from his. He once told a friend “you and I are able people, but Hertha is a genius.” She began her own studies of the electric arc, solving the pressing problem of why they would flicker and hiss. She showed this was a result of oxygen coming into contact with carbon rods used to create the arcs. She patented a number of improvements to arc lights and published 12 articles on her advances. She was the first woman to deliver a paper to the Institution of Electrical Engineers (IEE), which was more progressive than other institutions and always allowed women to attend meetings. She was also able to present three papers to the British Association for the Advancement of Science (BAAS, now the British Science Association) in 1895, 1896 and 1898. She was elected a member of the IEE, recognized a professional qualification, in 1899; she was the sole female full member of the institution until 1958. Her cousin Marcus Hartog used her 1900 lecture at the International Electrical Congress in Paris to argue that the British Association for the Advancement of Science shouls allow women on their committees. Denied the right to present her paper to the Royal Society due to her sex, renown engineer John Perry (and Will's former colleague) presented it on her behalf in 1901. After she published her textbook The Electric Arc, Perry proposed her as Fellow of the Royal Society but they rejected this (as she was married, and hence had no independant legal standing). But in 1904, she became the first woman to present her own paper ‘The Motion of Ripples in Sand and Wave’ to the Royal Society. By 1906 she was the first woman to win the Hughes Medal, for her work on ripples and the electric arc.⁠
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In Paris in 1903 she met Marie Curie and they became close friends, both physicists who collaborated with their physicist husbands and dedicated to social causes, and concerned about the role of women in society. They visited whenever Ayrton was in France. Ayrton vocally defended Marie, when Pierre died and the British press identified him (rather than Marie) as the discovered of radium, writing ‘Errors are notoriously hard to kill, but an error that ascribes to a man what was actually the work of a woman has more lives than a cat.’ Then in 1911, Marie won the Nobel for chemistry but endured a scandal in when her affair with married physicist Paul Langevin. Ayrton defended her again, and Marie and her daughters took refuge with the Ayrtons in England for two months. She was deeply involved in the women’s suffrage movement, marched in many marches (and recruited her friend Marie Curie to the cause).⁠
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After poisoned gas was used as a weapon during WWI, she put her expertise in fluid dynamics to work trying to develop a means of removing gas from the trenches. She also invented a fan and despite initial resistance from the War Office was able to demonstrate its effectiveness in protecting soldiers from poison gas and she herself organized production of her first manually operated fans in 1916. By 1917 she had developed a new, mechanically operated fan, more resistant to high winds, and she again fought War Office bureaucracy and organized the production of 104,000 sent to the Western Front.⁠ Her research on fans was later used to improve ventilation in mines and sewers. She continued to study vortices until she died. She left much of her estate to the IEE.

*Apparently, the character Mirah, in George Eliot's novel Daniel Deronda, is based on Hertha. You might recall that George Eliot was also friends with another mathematician I've portrayed, Sofia Kovalevski. The sentence "In short, woman was a problem which, since Mr. Brooke's mind felt blank before it, could hardly be less complicated than the revolutions of an irregular solid," from Eliot's Middlemarch, is undoubtedly due to her friendship with Kovalevski. I like to imagine George Eliot was quietly a math groupie. 

 References 

Elizabeth Bruton, The life and material culture of Hertha Marks Ayrton (1854–1923): suffragette, physicist, mathematician and inventor, Science Museum Group Journal, Autumn 2018, Issue 10 Article DOI: http://dx.doi.org/10.15180/181002

Ayrton, Hertha. “The origin and growth of ripple-mark.” Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 84, no. 571 (1910): 285-310.

Kim Martini, The origin of ripples and other fantastic fluid experiments by Hertha Marks Ayrton, Deep Sea News, April 28, 2016.

Hertha Ayrton, Wikipedia, accessed February, 2021.

Joan Meiners, Meet Hertha Ayrton, the mathematician who cleared WW1 trenches of poisonous gas, Massive Sci, June 5, 2020.

Archives Biographies: Hertha Ayrton, The Institute of Engineering Technology, accessed February, 2021

The Mother of Aquariophily, Jeanne Villepreux-Power and the Mystery of the Paper Nautilus

Jeanne Villepreux-Power, linocut 11" x 14" by Ele Willoughby, 2019

I have another scientific Cinderella story for you. A daughter of a poor family makes an epic walk to the big city, makes a gown for a princess, finds her own merchant prince and reinvents herself as scientist and inventor, solves marine biological mysteries and is a trailblazer for women in science!

Jeanne (sometimes Jeannette) Villepreux was born in 1794 in Juillac, the eldest daughter of a humble shoemaker and a seamstress who died when she was young. As a child, her education consisted merely of learning to read and write. When she reached 18, she walked the 400 km to Paris to try to make her fortune as a dressmaker. She found a job as an apprentice to a society dressmaker, thanks to her artistry and skill as an embroiderer. Within four years she had made a name for herself when she made the wedding gown of Sicilian Princess Caroline for her marriage to Charles-Ferdinand de Bourbon, future Duc de Berry and nephew of the King Louis XVIII. Through this newfound fame, she met a wealthy Irish merchant James Power, who was based in Italy. She taught herself English and Italian before the couple married and moved to Sicily in 1818. In her new home, she dedicated herself to her studies, natural history and inventorying the island’s ecosystem, both on and offshore. Messina, where the couple lived, was a natural draw to visiting scientists.  As a avid reader with an excellent memory, she educated herself rapidly and became well-connected with respected scientists. She travelled the island gathering minerals, fossils, butterflies and shells.

She had a particular interest in molluscs and their fossils, as well as one of their predators, the mysterious greater Argonaut (Argonauta argo) called the paper nautilus, which she studied from 1832 to 1843. The sheltered bay at Messina made it easy for her to see life under the calm waters. Despite its name, the paper nautilus is more closely related to octopuses than the nautilus. These rarely seen animals had long be the subject of myths; people commonly believed they stole their shells and even, thanks to Aristotle's wild conjectures, that they employed them as boats with the large dorsal arms as sails, to sail on the surface of the ocean. In 1932, she invented the aquarium to allow her to better study these marine animals, working with local fishermen who would bring her buckets of argonauts in seawater. She had a glass one for study, a submersible one, which fit in a cage, and a cage, known as "cages à la Power" which could be anchored at sea to study animals in their own environment since argonauts had not fared well in captivity. She methodically developed techniques to care for and feed marine creatures and change the water in the aquaria. She tracked how they fed, how they grew, moved and developed. The source of the shells remained mysterious, even after multiple experiments. Eventually she had the idea to damage a shell, and observe the animal within the cage when it was supplied with broken pieces of shells. She patiently watched for hours on end and was rewarded; she saw the animal repair its shell with the membranes on its front arms (which Aristotle mistook for sails). The membranes in fact secrete calcite, and the animal gently crafted and repaired its shell, evidence that it had created the shell itself.

She found not only that the paper nautilus did produce its own shells but that these were egg-sacks. She did the first studies of how these creatures reproduce. Argonauts have extreme sexual dimorphism; the females are twelve times as large as the males and the tiny males had not yet even been identified by science. She deduced that the small organisms which accompanied the egg sacks must be the male of the species, but later the truth was revealed to be even less probable; they were simply detached male reproductive organs which attach themselves to the female mantle. But, she was right to deduce these were part of the species' reproduction, yet her male peers dismissed her observations, insisting these were merely parasitic worms. She observed how the animals increase their shell sizes three times from August to December to make room for their young. She reported her results to the Academy of Catania in 1934 (and then was elected a member of this learned society) and in 1935 she sent her results to Paris to the Academy of Science. Her results were well received in Europe, though she faced some of her male peers doubted her; French zoologist Henri Marie Ducrotay de Blainville insisted argonauts scavenged their shells to the French Academy in 1936. She did not allow this to discourage her and she persisted in her work. Others like Sir Richard Owen, who defended her work in 1839 to the London Zoological Society and French malacologist Sander Rang who presented one of her papers, supported her research.

She published her first book in 1839, in French Observations et expériences physiques sur plusieurs animaux marins et terrestres (Observations and Physical Experiments on Several Marine and Terrestrial Animals) which included her evidence solving the mystery of the paper nautilus’ shell and her second in Italian, Guida per la Sicilia, a comprehensive guide to the local environment, including descriptions and illustrations of hundreds of plants, animals, fossils and minerals, was published in 1842. In 1860, she published a paper on the Octopus vulgaris, and showed that the animal uses tools, including stone to hold open Pinna nobilis, the noble pen shell or fan mussel shells.

She wrote passionately about conservation issues and developed the principles of sustainable aquaculture in Sicily. She was a talented artist and made lovely scientific illustrations of the species she observed. She was recognized for her science by her peers, admitted as the first woman in the scientific academy Catania Accademia Gioenia, as a correspondent member of the London Zoological Society and sixteen other learned societies. The famous biologist and paleontologist Sir Richard Owen called her "Mother of Aquariophily."

Tragically when she and her husband left Sicily in 1843, she lost most of her collections, many of her records and scientific illustrations in a shipwreck. This loss may explain how she gave up experimenting in her later life, though she continued to write and speak publically about the natural world. The couple divided their time between Paris and London. She fled Paris during a siege by the Prussian Army in 1870, and she returned to Juillac where she died in 1871.

A crater on Venus has been named Villepreux-Power in her honour in 1997.

References

Jeanne Villepreux-Power, Wikipedia, accessed December, 2019

Jeanne Villepreux-Power, Britannica.com, accessed December, 2019  

Lauren J. Young, The Seamstress And The Secrets Of The Argonaut Shell, Science Friday, June 20, 2018

Celeste Olalquiaga, 'The Artificial Kingdom,' Pantheon Books, 1998.

Allcock, A. & Von Boletzky, Sigurd & Bonnaud, Laure & Brunetti, Norma & Cazzaniga, Nestor J. & Hochberg, Eric & Ivanovic, Marcela & Lipinski, Marek & Marian, José & Nigmatullin, Chingis & Nixon, Marion & Robin, Jean-Paul & Rodhouse, P. & Vidal, Erica. (2015). The role of female cephalopod researchers: past and present. Journal of Natural History. 49. 1235-1266. 10.1080/00222933.2015.1037088.