Bibha Chowdhuri, from the heights of the Himalayas down into the mines, studying cosmic rays and discovering mesons

Bibha Chowdhuri, linocut, 11" x 14" by Ele Willoughby, 2025

The second Printer Solstice prompt is 'even', so I made a portrait about the discovery of mesons. When students are introduced to quarks, the fundamental particles, usually they learn how nucleons, that is, protons and neutrons are each made of trios of quarks. Quarks are weird because they have fractional charge (like +/- a third or two thirds of and electron's charge), and we only ever observe integer charge (say, things have, for instance -1e, 0 or +1e charge). They come in perfectly ridiculously named flavours: up, down, top, bottom, charm and strange (and of course, anti-up, anti-down, anti-top, anti-bottom, anti-charm and anti-strange). Little groups of three quarks can be stable and long-lived, and in fact, a significant proportion of the mass of regular, every day matter, what we call baryonic matter, can be explained by trios of quarks in neutrons and protons. So you can make a proton (+1e) with two up quarks (+2/3 e each) and one down quark (-1/3 e) and the math works out. But it's also possible to make matter with even numbers of quarks. These unstable particles are called mesons. Usually they are made with quark-antiquark pairs, but there are also some exotic mesons with four quarks. Long before we had developed the Standard Model and before quarks themselves were proposed (by Gell-Mann and Zweig, in 1964) as an explanation for baryonic matter, mesons were proposed as an explanation for nuclear forces (what held the neutron and the proton within the nucleus - a real mystery as this force must overcome electromagnetic repulsion) by theorist Hideki Yukawa in 1934 and they were first observed by Bibha Chowdhuri (1913-1991) and her supervisor Debendra Mohan Bose in 1940. In the early days of particle physics, before physicists were accelerating and smashing particles together at incredible speed and energies, the easiest way to observe these particles was in naturally occurring cosmic rays or high-energy ionizing radiation from space which rains down on our atmosphere. Physicists literally climbed mountains and used hot air balloons to get as much altitude as possible to measure these particles. At the time, Chowdhuri, Bose and others called these particles they observed in cosmic rays "mesotron showers" but we now know them as mesons. Seven years after Chowdhuri and Bose published their discovery another physicist, Cecil Powell performed similar experiments. He was granted the 1950 Nobel Prize for working on photographic methods of studying nuclear processes and his subsequent "discovery" of the pi-meson. He had access to higher quality of photo emulsion than his Indian colleagues did during WWII, but his measured mass for the particle was very similar to their results. He did acknowledge their work during his Nobel acceptance (well, he called her "Chaudhuri") but essentially, he repeated their discovery with somewhat higher precision, as well as observing muons decay into electrons. The photographic emulsion method itself, in turn, was pioneered by another under-appreciated woman, Marietta Blau (and her student Hertha Wambacher). Blau was also nominated for, but did not win, the 1950 Nobel Prize. Blau discovered what she called "disintegration stars" which were particle tracks of high-energy cosmic rays nuclear reactions recorded in photographic plates; as a Jewish Austrian scientist, her research was interrupted in 1938; mercifully, she was able to secure a position in Oslo and leave Austria, but having to flee for her safety negatively impacted her career and delayed recognition of her research. One could easily argue that Chowdhuri, Bose, and Blau were at least as qualified to win the 1950 Nobel as Powell.

Bibha was born in Kolkata, to a family of the landlord Zamindar class. Her father Banku Behari Chowdhuri was a doctor. Her mother, Urmila Devi's family were followers of Brahmoism, a reformist religion which branched off of Hinduism, rejecting polytheism, rituals and the caste system.  To marry her mother, Banku had to convert and was outcast from Hindu society. He even lost the right to his parent's property. Education of women in India at that time was quite rare, but Brahmo Samaj, the societal aspect of the Brahmoist religion, promoted education, especially of women and girls. Several of the Chowdhuri children (Bibha had four sisters and one brother) were highly and equally educated, while in pre-independence India, the education of girls was so extremely rare as to be virtually non-existent; their expected role was to marry and serve their husbands. None of the Chowdhuri siblings married, which was a rare privilege at the time for the girls.

Detail of my screen print "Cloud Chamber" showing particle trails in yellow
as recorded in a Wilson Cloud Chamber against a cloudy blue sky.

She studied physics at the Rajabazar Science College of Calcutta University, where she was the only woman in a class of 24 to graduate with an M.Sc. in 1936. She joined the Bose Institute in 1939 to study cosmic rays with the legendary Debendra Mohan Bose, who had worked with C.T.R. Wilson to build the Wilson Cloud Chamber (a tool for recording the tracks of high energy particles in a supersaturated cloud-like vapour or water or alcohol).  He has been reluctant to take her on as a student, and told her he did not have any projects suitable for a woman, but she persisted. He had built a cloud chamber on his return to India, and was building his reputation as India's first cosmic ray physicist. She published her paper in the Transactions of the Bose Institute based on photographic plates exposed to cosmic rays for four months at an altitude of 12,000 feet (3600 m) atop Sandakphu, a mountain peak in Nepal, shown in my portrait. She set up the instrumentation at each site and gathered the exposed plates afterwards for analysis, travelling on horseback - a potentially scandalous action for an unmarried Indian woman in the 1930's. Her research showed the superiority of using photographic plates to employing cloud chambers, and the Bose Institute thenceforth adopted photographic plates.

Next, she proceeded to expose Ilford R2 and the new halftone photographic plates at three different altitudes at Darjeeling at 7000 feet (2000m), Sandakphu at 12,000 feet (3600 m) and Pharijong at 14,000 feet (4300 m), to study what they called "mesotron showers." Yukawa had proposed the particles we now call mesons, to explain the strong nuclear forces which confine protons and neutrons within the nucleus, just a few years previous, and the race was on to confirm their existence. She exposed plates directly to air, and some under paraffin wax or water. Plates were exposed for 150 to 202 days. Using a high-power microscope, she and Bose examined the lengths, spacing and scattering of the recorded tracks to determine the mass, energy and momentum of the particles they recorded. Scattering angle could be linked to mean energy, and the mean grain spacings along tracks could be used to calculate velocities. They found that most tracks were from particles of higher velocities and lower kinetic energies than protons, suggesting, importantly that they were lower mass than protons, as expected fro Yukawa's theoretically proposed particle. She published four papers in Nature from 1940-1942 with her results. Bibha Chowdhuri was the first person to measure the mass of a meson and she quickly published even more precise results. She realized they would need improved photographic plates to continue the research, but these were unavailable due to imposed WWII restrictions. Cosmic ray research at the Bose Institute stopped. 

Chowdhuri went to England to pursue her doctorate and join the cosmic ray research laboratory of Patrick Blackett in 1945, with thesis advisor J.G. Wilson, when extensive air showers in cosmic rays was the hot topic in particle physics. She recorded the spectrum of penetrating extensive air showers taking photographic plates within a cloud chamber surrounded by Geiger counters. She defended her thesis, "Extensive Air Showers associated with Penetrating Particles," in 1949. Extensive Air Showers refers to the cascade of subatomic and ionized nuclei particles that we get when cosmic rays enter our atmosphere from space and collide with the nuclei of various air molecules (discovered by Bruno Rossi in 1934); it then extends itself through several more generations of collisions as shown in my portrait. Interviewed by the Manchester Herald, Bibha said, "Women are terrified of physics - that is the trouble. It is a tragedy that we have so few women physicists today. In this age when science, and physics particularly, is more important than ever, women should study atomic power; if they don't understand how it works, how can they decide how it should be used? I can count the women physicists I know, both in India and England, on the fingers of one hand." The same year, Blackett had won the Nobel for "his development of the Wilson cloud chamber method, and his discoveries therewith in the fields of nuclear physics and cosmic radiation." 

Chowdhuri applied to do post-doctoral work in Paris at École Polytechnic with Louis Leprince-Ringuet on photo emulsions, seeking financial support from the government of India. She had a letter of recommendation from J.G. Wilson who was one of her thesis examiners. Her application was sent to Homi Babha for comment and he wrote Wilson to inquire whether it would really be worth the investment for her to study photo emulsions for 6 months when her doctorate was on extensive air showers. Both men seem to have forgotten her prior world-class research on photographic methods with Bose, and Wilson backed off his prior recommendation and replied that, "Miss Chowdhuri cannot be regarded as a first-class physicist but she can make good progress under fairly done guidance" and as she had done good work on air showers, she should "not be encouraged to go into a new field of work." Yet, it was photo emulsion work which led to Powell's Nobel.

After her brief stay in Paris she returned to India to work at the Tata Institute of Fundamental Research (TIFR), with a glowing recommendation from Blackett (in complete contrast with Wilson's lukewarm support). She worked as a Research Fellow with the Experimental Physics Group for 5 years, the first woman at TIFR. This was the lowest rank at which they could hire her; all the contracts were written with the presumed pronoun for a physicist of "he." She was in charge of the Cloud Chamber Group investigating penetrating particles in extensive air showers.

She decided to apply for a Senior Research Fellow position in the cosmic-ray project at Bengal Engineering College, Shibpur in 1954. The post had a lower salary and the college was not known for basic research. Her reasons for this decision are unclear, as are Bhabha's for writing her a letter or recommendation but not trying to persuade her to stay. Perhaps she wished to be closer to home, but within a year she left for Paris where she worked with Leprince-Ringuet and studied many new K mesons in cloud chambers in the Alps. While in Paris, her American colleague, a Visiting Fullbright Scholar Wayne Hazen invited her to teach at the University of Michigan. She spent two years working with him and as a Visting Lecturer in physics at the University of Michigan, then worked briefly in Bruno Rossi's MIT lab working on Plastic Scintillators for detecting large air shows and collaborating on planning a new extensive shower array in New Mexico. 

In 1961 she joined the Physical Research Laboratory (PRL) in Ahmedabad. Despite her two decades of experience she was only offered a temporary position as a Senior Research Fellow but she was interested and took the job. After beginning her career studying extensive air showers high in the Himalayas, at PRL she investigated  high energy muons in cosmic rays at a depth of 700 feet (2000 m) in the Kolar Gold Field with simultaneous measurements at ground level at TIFR in collaboration with Vikram Sarabhai, director of PRL. She and her students and technicians donned miner's hats to descend daily in the elevator cage down to their instruments, sometimes carrying their own oxygen if conditions were unsafe. Sarabhai's untimely death interrupted her future research plans. Once again she saw her research interrupted by factors beyond her control.

After retiring from PRL she returned to Kolkata and continued her research, collaborating with colleagues at Calcutta University, the Saha Institute of Nuclear Physics, the Variable energy Cyclotron Centre and the Indian Association for the Cultivation of Science looking at nucleus-nucleus interactions at relativistic energies to learn about  astrophysics and cosmic rays.

She was publishing research until the end of her life, though after returning to India, she chose to publish only in Indian journals. She was never made a fellow of any of the Indian scientific societies. She was woefully under-appreciated during her lifetime; it seems likely she faced gender discrimination and was underestimated by her male peers. She became less and less remembered internationally, and when she died in 1991 no obituary appeared in any scientific journal, but her story and accomplishments have begun to be recognized posthumously. In 2019, the International Astronomical Union named a star "Bibha," Bengali for "ray of light," in her honour. In 2020, when then Indian government decided to establish 11 named research chairs after famous women scientists, the physics chair was named after Bibha Chowdhuri.

References 

Bibha Chowdhuri, Wikipedia, accessed December, 2025

Bibha Chowdhuri, Mirror Wellesley Blog, accessed December, 2025

Bhattacharya, Amitabha. The woman who could have won a Nobel. The Telegraph, November 28, 2018. 

Jacob, Julie. Bibha Chowdhuri: A Missed Nobel Prize and an Unfulfilled Prophecy. The Lovepost. January 14, 2021.

Mondal, Naba K. Bibha Chowdhuri and Her Remarkable Scientific Endeavours. Resonance. Vol. 28, no. 10, DOI: https://doi.org/10.1007/s12045-023-1686-1. October, 2023

Nagarajan, Archana. Bibha Chowdhuri. Sci-Illustrate. August 8, 2019.

Sinha, Atreyee and Ritam Sinha, Bibha Chowdhuri: A Ray of Light. Building from Diversity, CTAO News. November 30, 2022.

Roy, S.C. and Rajinder Singh. Bibha Chowdhuri - Her Cosmic Ray Studies in Manchester. Indian Journal of History of Science. 53.3 (2018) 356-373. DOI: 10.16943/ijhs/2018/v53i3/49466

Roy, Suprakesh and Rajinder Singh. Bibha Chowdhuri - The First Woman Scientist at the TIFR. Physics News Tata Institute of Fundamental Research, Vol 51 (1-2), Jan-June, 2005

The Nobel Prize in Physics 1948, NobelPrize.org, accessed December, 2025

Eunice Newton Foote and the Greenhouse Effect

Eunice Newton Foote, linocut, 9.25" x 12.5" by Ele Willoughby, 2025

Once again, I am taking part in the Printer Solstice collection of printmaking prompts, starting at the winter solstice (here in the northern hemisphere). The prompts this year are mathematical in scheme, which works well for me, and my on-going series of portraits of women in STEM. The first prompt, "addition" made me think of the greenhouse effect, excess additional atmospheric CO2 and the resulting excess terrestrial temperatures. It made me think of a scientist who has been on my to do list for years: Eunice Newton Foote. The reason I have not tackled her portrait is that there are no known photographs of Eunice Newton Foote. I had hoped, since I knew that climate scientist Katherine Hayhoe and historians of science and others were seeking her portrait, that perhaps I should just wait patiently. As time wore on, we have learned more about Foote's life, but her portrait has not been found. However the waters have been muddied, as more and more people illustrate their posts and even published newspaper articles with images incorrectly labelled as Eunice Newton Foote. So I decided it was my time to add my image of her, to offer another imagined illustration, based on what we do know, rather than misinformation. It's quite easy to get the wrong photograph associated with a little-known historical woman in science, so I can understand how this has happened, but it frustrates me. Eunice Newton Foote deserves to be remembered as a scientist, inventor and activist, and she deserves not to be conflated with her daughters, or worse, random historical women and AI-generated nonsense.

My lino block print portrait shows the amateur pioneering American scientist, inventor and women's rights advocate Eunice Newton Foote (1819-1888) who did the earliest experiments to show the insulating effect of certain gases and correctly concluded that increasing carbon dioxide levels would affect atmospheric temperature and climate, which we now call the Greenhouse Effect. Each print is burnished by hand on lovely cream-coloured Japanese paper, 9.25" x 12.5" in a gradient of cyan, pale blue and bronze.

This is Mary Foote Henderson, again. She is not her mother.
This is specifically a detail of a photo by the Brady Studio. 
Record Unit 7075 - The Henderson Family Papers, 
1868-1923, Smithsonian Institution Archives. 
You can check for yourself.

Eunice Newton was born in Connecticut to Thirza and farmer and entrepreneur Isaac Newton Jr., a distant relative of famed physicist Sir Isaac Newton, who had six sons and five other daughters (though girl died at two years of age). They moved the family to Ontario County in western New York, which was a centre of social activism for abolitionists, dress reform activists, mystics, temperance advocates, and women's rights campaigners. She attended the Troy Female Seminary, a women's preparatory school established by feminist Emma Willard, which offered a much broader curriculum than the typical women's finishing school and where students were actually encouraged to attend science courses at the nearby Rensselaer School, run by a scientist, education innovator and proponent of women's education Amos Eaton. Eaton introduced practical experimentation in the lab alongside teaching theory.

In 1841 Eunice married lawyer Elisha Foote, who trained in Johnstown, New York, under Judge Daniel Cady, the father of women's rights activist Elizabeth Cady Stanton. Elisha bought a house, then deeded it to Cady who gave it to his daughter. Elisha became a judge in Seneca County, but resigned in 1846. Eunice was friends with Elizabeth Cady Stanton and attended the 1848 Seneca Falls Convention, the first women's rights convention. She and Elisha both signed the Declaration of Sentiments, described by Frederick Douglas as the "grand movement for attaining the civil, social, political, and religious rights of women." Eunice was one of the five women who prepared the convention proceedings for publication.

Eunice and Elisha both worked as inventors. Elisha filed a patent in 1842 on a thermostatically controlled cooking stove invented by Eunice presumably because as a married woman, Eunice would have been unable to defend her patent in court. Eunice told Elizabeth Cady Stanton she thought half of all patents filled were in fact inventions by women with the patents taken out by men. In fact, in 1857, Elisha defended the patent and got a substantial settlement for infringement.

Mary Foote Henderson, not her mother.

Elisha went back to working as a lawyer, and Eunice built a lab in their home. The pair had two daughters: writer, developer, suffragette and social activist Mary who became known as "The Empress of Sixteenth Street" and writer and naturalist Augusta, who wrote The Sea-Beach at Ebb-Tide, regarded as a seminal work on the intertidal biology of the United States. The family moved to Saratoga Springs, NY, where Elisha specialized in patent law, then became the Commissioner of Patents, then served on the Board of Examiners-in-Chief for several years.

In her lab Eunice investigated the effect of sunlight on various gases. Using two glass cylinders, each equipped with two mercury-in-glass thermometers, she used an air pump to evacuate the air from one cylinder and compress it in the other cylinder. When their temperatures equalized she placed them both in the sunlight and looked for temperature variances. She contrasted this with when the cylinders were placed in the shade and also tested the temperature results by dehydrating one cylinder and adding water to the other, to measure the effect of dry versus moist air. She noted that the amount of water in the air did affect the temperature. She tried this experiment using air, carbon dioxide (then known as carbonic acid gas) and hydrogen. The cylinder of carbon dioxide in sunlight became hotter than the others. She wrote: "The receiver containing this gas became itself much heated—very sensibly more so than the other—and on being removed [from the Sun], it was many times as long in cooling". Considering the history of Earth, she wrote, "An atmosphere of that gas would give to our earth a high temperature; and if, as some suppose, at one period of its history, the air had mixed with it a larger proportion than at present, an increased temperature from its own action, as well as from increased weight, must have necessarily resulted." She clearly understood and expressed the impact of increased atmospheric carbon dioxide and what we now call the Greenhouse Effect. She submitted these findings as a paper entitled "Circumstances Affecting the Heat of the Sun's Rays", that she submitted for the tenth annual AAAS meeting, held on August 23, 1856, in Albany, New York, where it was presented by physicist Joseph Henry on her behalf. While not published in the proceedings of the AAAS meeting, it was published in the 1856 edition of the American Journal of Science and Arts; it was the first known physics publication in a scientific journal by an American woman. Summaries were also included in several international scientific journals and periodicals. Eunice was praised in the September 13, 1856, issue of Scientific American for backing up her theories with experiments, noting "she was deeply acquainted with almost every branch of physical science"

C'mon people. This one is literally labelled

Mrs. Henderson. It's a photo by Ida

Hindman in 1895, for the Washington

Sketch Book.

Eunice's experiment was not without precedent.  In the 1770s, Horace Bénédict de Saussure found that altitude impacted solar heat in an enclosed cylinder and the 1820s Joseph Fourier theorized that atmospheric gases trapped solar heat. But only Eunice Foote had drawn the conclusion that solar heat would be increased by the presence and proportion of C02 or water vapour in the atmosphere. Three years after Foote's publication, in 1859, physicist John Tyndall performed a more sophisticated experiment which showed several gases both trapped and emitted infrared thermal radiation rather than simply investigating the effect of sunlight. He published "Note on the Transmission of Radiant Heat through Gaseous Bodies" in the Proceedings of the Royal Society, where he cited Claude Pouillet's work on solar radiation through the atmosphere, but did not cite Foote's work. It's unclear if he failed to note her results or did not see their relevance. He did not mention water vapour, carbon dioxide, or climate until several publications later. A very skilled and well-trained (though regrettably quite chauvinistic) physicist, Tyndall is often credited with the earliest evidence of the Greenhouse Effect. Alternatively, the Greenhouse Effect is sometimes credited to physical chemist Svante Arrhenius, who in 1896, used physical chemistry to estimate how much atmospheric CO2 would increase the Earth's surface temperature. There is no denying though that Eunice Newton Foote was the first to specifically argue that our climate would warm with increasing atmospheric CO2.

Foote went on to investigate moisture content and which gases in the air could generate static electricity. She hypothesized that electric charges and fluctuations in atmospheric pressure might explain the Earth's magnetic field and polarity, which we now know is not the case. Her paper "On a New Source of Electrical Excitation" was read by Henry at the 1857 AAAS meeting in Montreal, and published in the Proceedings of the American Association for the Advancement of Science, the first physics publication there by an American woman. 

In 1860 Eunice filed a patent in her own name for a shoe and boot insert made of a single piece of vulcanized rubber to "prevent the squeaking of boots and shoes". In 1864 she developed a new cylinder-type of paper-making machine. In 1868 she invented skates without straps. 

She died in 1888 in Lenox, Massachusetts. She fell into obscurity until historians began researching early women scientists in the 1970s and more recently, climate scientists have revisited and worked to highlight her early contributions to their science.

As her story has been rediscovered people have made a concerted effort to find images of her. Though there are many photographs of her two daughters, especially Mary Foote Henderson, and Augusta Newton Foote Arnold, and her husband Elisha Foote Jr, there are no known photographs, or painted portraits of Eunice. Many stories, including in published newspaper stories, are illustrated with photographs of Mary misidentified as Eunice, or worse, with AI-generated slop images based on completely unrelated women. All we have, so far, is her 21 July 1862 passport application, where she is described as having an oval face, dark brown hair, blue-grey eyes, a small ordinary chin, an ordinary nose, a full forehead and a rather large mouth. Having looked at these photos carefully, I have convinced myself that Mary resembles her father, so I don't even think we can rely on family resemblance and let Mary's image give us an idea of what Eunice looked like. So I chose to illustrate her, without showing her full face, at work in her lab, in Victorian clothing like what other women doing similar work. Her paper describes her experiments with air pump, and two large cylinders with two thermometers each, so I could illustrate these as described.

References

Augusta Foote Arnold, Wikipedia, accessed December, 2025

Elisha Foote, Wikipedia, accessed December, 2025

Eunice Newton Foote, Wikipedia, accessed December, 2025

Foote, Eunice. "Circumstances Affecting the Heat of the Sun's Rays". The American Journal of Science and Arts. 22 (66). New York, New York: G. P. Putnam & Company: 382–383. ISSN 0099-5363. OCLC 1280516952. September, 1856.

Foote, Eunice. "On a New Source of Electrical Excitation". Proceedings of the American Association for the Advancement of Science: Eleventh Meeting. Cambridge, Massachusetts: Joseph Lovering: 123–126. OCLC 923936325.  August, 1857.

Huddleson, Amara. Happy 200th birthday to Eunice Foote, hidden climate science pioneer,  Climate.gov, July 17, 2019.

Josse, Tess. August 1856: Eunice Foote Concludes that Carbon Dioxide Could Warm The Atmosphere, Three Years Before John Tydall Did, APS News, July 12, 2023. 

Kurland, Zoe, Katie Hafner, Elah Feder and The Lost Women of Science Initiative, The Woman Who Demonstrated the Greenhouse Effect, Scientific American,  November 9, 2023.

Mary Foote Henderson, Wikipedia, accessed December, 2025

McNeill, Leila  "This Lady Scientist Defined the Greenhouse Effect But Didn't Get the Credit, Because Sexism". Smithsonian. Washington, D.C.: Smithsonian Institution. ISSN 0037-733December 5, 2016.