John Tyndall ( / ˈ t ɪ n d əl / ; 2 August 1820 – 4 December 1893) was an Irish physicist. He became famous for studying diamagnetism in the 1850s. Later, he discovered important things about infrared radiation and the physical properties of air. In 1859, he showed how carbon dioxide in the air is linked to the greenhouse effect.

Tyndall also wrote over a dozen science books that shared the latest physics research with many people. From 1853 to 1887, he was a professor of physics at the Royal Institution in London. In 1868, he was chosen as a member of the American Philosophical Society.

Early years and education

John Tyndall was born in Leighlinbridge, County Carlow, Ireland. His father was a local police officer. His family came from Gloucestershire, England, and moved to southeast Ireland around 1670. Tyndall attended local schools, including Ballinabranna Primary School, in County Carlow until his late teens. He likely helped teach students near the end of his time there. At school, he studied subjects like technical drawing, mathematics, and how to apply them to land surveying. In his late teens, he was hired as a draftsman by the Ordnance Survey of Ireland in 1839. He later moved to work for the Ordnance Survey of Great Britain in 1842. During the 1840s, a boom in railway construction created demand for Tyndall’s land surveying skills. Between 1844 and 1847, he worked on railway planning projects and earned a good income.

In 1847, Tyndall chose to become a teacher of mathematics and surveying at Queenwood College, a boarding school in Hampshire. He later wrote that he wanted to continue learning and accepted the teaching job when railway work slowed down. Another teacher at Queenwood was Edward Frankland, who had previously worked as a laboratory assistant for the British Geological Survey. Frankland and Tyndall became close friends. Because of Frankland’s knowledge, they decided to study science in Germany. At the time, German universities were more advanced than British ones in experimental chemistry and physics. British schools focused more on subjects like classics and mathematics. In summer 1848, the pair moved to Germany and enrolled at the University of Marburg, where Robert Bunsen was a respected teacher. Tyndall studied under Bunsen for two years. Professor Hermann Knoblauch also had a strong influence on Tyndall, and they remained in contact through letters for many years. Tyndall’s thesis at Marburg, completed in 1850, was a mathematical study of screw surfaces, written under Friedrich Ludwig Stegmann. He stayed in Germany for another year, researching magnetism with Knoblauch. During this time, he visited the laboratory of Heinrich Gustav Magnus, Knoblauch’s teacher. Today, it is clear that Bunsen and Magnus were among the best science teachers of their time. When Tyndall returned to England in summer 1851, he likely had the best education in experimental science available in England.

Early scientific work

John Tyndall's early scientific work focused on magnetism and diamagnetism. He conducted experiments on these topics from 1850 to 1856. His most important reports were the first two, written with a scientist named Knoblauch. One of these reports, titled "The magneto-optic properties of crystals, and the relation of magnetism and diamagnetism to molecular arrangement," was published in May 1850. The reports described a creative experiment and a creative explanation of the results. These studies, along with other magnetic research, quickly made Tyndall well-known among top scientists of his time. In 1852, he was chosen as a Fellow of the Royal Society. When seeking a research position, he asked the editor of a major German physics journal, Poggendorff, and other respected scientists to write letters of recommendation. In 1853, he was appointed Professor of Natural Philosophy (Physics) at the Royal Institution in London. This appointment was greatly influenced by the respect his work had earned from Michael Faraday, the leading expert in magnetic studies at the Royal Institution. About ten years later, Tyndall was named to take over the roles previously held by Michael Faraday at the Royal Institution after Faraday retired.

Alpine mountaineering and glaciology

In 1856, John Tyndall traveled to the Alps for scientific research and became one of the first people to climb the mountains for study. He returned to the Alps every summer after 1856. Tyndall was part of the first group to reach the top of the Weisshorn in 1861 and led one of the earliest teams to climb the Matterhorn in 1868. His work is connected to the "Golden age of alpinism," a time in the mid-1800s when many difficult Alpine peaks were first reached by climbers.

In the Alps, Tyndall studied glaciers, especially how they move. His ideas about how glaciers flow caused disagreements with other scientists, including James David Forbes. Earlier research on glacier movement was done by Forbes, but he did not know about a process called regelation, which was discovered later by Michael Faraday. Regelation helped explain Tyndall’s findings. Forbes disagreed with Tyndall’s explanation. A public argument also arose about who should receive credit for scientific discoveries. Supporters of Forbes believed he deserved most of the credit, while Tyndall thought credit should be shared more broadly. Tyndall said, "The idea of semi-fluid motion belongs entirely to Louis Rendu; the proof of the quicker central flow belongs in part to Rendu, but almost wholly to Louis Agassiz and Forbes; the proof of the retardation of the bed belongs to Forbes alone; while the discovery of the locus of the point of maximum motion belongs, I suppose, to me." After both men died, their biographers continued the disagreement. Although everyone tried to be fair, no agreement was reached. Some aspects of glacier movement remained unclear or unproven.

Many landforms and places are named after John Tyndall, including Tyndall Glacier in Chile, Tyndall Glacier in Colorado, Tyndall Glacier in Alaska, Mount Tyndall in California, and Mount Tyndall in Tasmania.

Main scientific work

John Tyndall’s work on glaciers led him to study the research of Horace Bénédict de Saussure on how sunlight heats the Earth and the idea developed by Joseph Fourier, later explored by Claude Pouillet and William Hopkins, that sunlight passes through the atmosphere more easily than heat from the Earth, which is now called the greenhouse effect. In 1859, Tyndall began experiments to see how visible and invisible heat (infrared radiation) interacts with gases and tiny particles in the air. He used a device called an electro-magnetic thermopile, invented by Macedonio Melloni, to create a method called differential absorption spectroscopy.

On May 9, 1859, Tyndall started his experiments but had little success at first. He improved his tools and on May 18 wrote in his journal, “Experimented all day; the subject is completely in my hands!” On May 26, he shared his findings with the Royal Society, stating that little was known about how heat from Earth moves through gases.

On June 10, Tyndall presented his research at a Royal Society lecture. He showed that gases like coal gas and ether strongly absorb infrared radiation and confirmed the greenhouse effect. He explained that sunlight enters Earth’s atmosphere, but heat from the Earth changes as it radiates back into space. The atmosphere allows sunlight in but traps some of the heat, causing the planet to warm.

Tyndall’s research on how heat interacts with air led to several discoveries:
– He measured how different gases, such as nitrogen, oxygen, water vapor, carbon dioxide, ozone, and methane, absorb infrared radiation. He found that water vapor absorbs the most heat, making it the main gas that controls Earth’s temperature. Before Tyndall, scientists believed in the greenhouse effect, but he was the first to prove it experimentally. In 1856, Eunice Newton Foote had shown that water vapor and carbon dioxide absorb heat, but she did not study infrared radiation specifically. Tyndall also showed that gases that are clear to the eye can emit infrared radiation.
– He studied how heat is absorbed and released by molecules during chemical reactions. He demonstrated that heat from reactions comes from the molecules themselves. He also showed how infrared light can be converted into visible light, a process he called calorescence. He often referred to infrared as “radiant heat” or “ultra-red undulations,” as the term “infrared” was not widely used until the 1880s. His work was later published in a book titled Contributions to Molecular Physics in the Domain of Radiant Heat.
– To study how light scatters in air, Tyndall removed dust and other particles from air samples. He used bright light to detect these particles and discovered that light scatters more when it passes through impurities. This discovery is now called the Tyndall effect. He built tools like the nephelometer to study aerosols and colloids using light. These tools later helped create the ultramicroscope.
– He observed a phenomenon called thermophoresis, where particles move toward a heat source. He noticed this while studying the Tyndall effect and described it in 1870.
– He found that liquid and vapor forms of certain substances absorb heat equally, molecule for molecule. Modern experiments show small differences, but Tyndall’s equipment could not detect them.
– He showed that visible light properties, like reflection and refraction, also apply to infrared radiation. This built on earlier work by scientists like Paul-Quentin Desains and Hermann Knoblauch.
– Using his knowledge of heat absorption, he created a system to measure carbon dioxide in human breath. This method is still used in hospitals today to monitor patients under anesthesia.
– He confirmed that ozone is a group of oxygen molecules by studying how it absorbs heat.

To create air without visible particles, Tyndall built a wooden box lined with glycerin, a sticky substance. After several days, particles in the air stuck to the box’s walls and floor, leaving the air inside clean. He used this “optically pure” air to test whether microorganisms cause decay. Broth samples in pure air stayed fresh for months, while those in normal air spoiled quickly. This supported Louis Pasteur’s work showing that microorganisms cause decay. However, in 1876, Tyndall could not consistently repeat this experiment.

Educator

John Tyndall was not only a scientist but also a science teacher and a strong supporter of science education. He spent much of his time sharing scientific knowledge with people who were not experts. He gave many public lectures at the Royal Institution in London to audiences who were not trained in science. In 1872, he traveled to the United States to give lectures about light, and many people who were not scientists paid to attend. A London newspaper in 1878 said, "Like Faraday before him, Professor Tyndall has made science both accurate and interesting to the public. His lectures at the Royal Institution are always very popular." Tyndall believed that teaching was a "noble and blessed calling." His books, written for people who were not specialists, helped him reach the largest audiences. He wrote over a dozen science books, many of which were translated into German and French and remained in print for many years.

In one of his books, The Forms of Water (1872), Tyndall wrote to young readers: "Here, my friend, our work is done. It has been a pleasure to teach you. You have worked hard, and I have helped you when needed. I want to teach everyone in this way—by showing you how to learn, but letting you do the learning yourself. You now understand some important ideas about nature. Goodbye, and I hope we meet again."

In his book Sound (1867), Tyndall wrote: "I have tried to make the science of sound interesting to everyone, even those who are not scientists. I describe experiments so you can imagine them happening." In the third edition of this book, he noted that earlier editions were translated into Chinese by the Chinese government and into German with the help of Hermann von Helmholtz, a well-known scientist in the study of sound. His first book, about glaciers (1860), also said it was written to interest people who were not experts in science.

Tyndall’s most famous book, Heat: A Mode of Motion (1863), was updated several times and remained in print for at least 50 years. James Clerk Maxwell said this book helped readers understand heat through clear experiments.

Tyndall’s books on heat (1863), sound (1867), and light (1873) described the latest scientific discoveries in physics. These books explained new ideas about their subjects, which Tyndall was the first to share with a wide audience. However, these books focused on experiments and avoided using complex math, such as calculus, even though calculus was part of the advanced understanding of heat, light, and sound at the time.

Demarcation of science from religion

Many of the British scientists who worked with John Tyndall during the 1800s were traditional in their religious beliefs. These scientists, such as James Joule, James Clerk Maxwell, and Lord Kelvin, studied topics like heat and light. They believed that science and religion could work together and support each other. Tyndall, however, was part of a group that supported Charles Darwin’s idea of evolution. This group wanted to keep science and religion separate. A well-known member of this group was Thomas Henry Huxley, an anatomist. Tyndall met Huxley in 1851, and they remained friends for life. Other members of the group included Edward Frankland, Thomas Archer Hirst, and Herbert Spencer.

Tyndall believed that science, which relies on knowledge and reason, should be kept apart from religion, which is based on faith and spirituality. In 1874, as president of the British Association for the Advancement of Science, he gave a speech in Belfast that praised Darwin’s theory of evolution. He argued that religion should not influence scientific knowledge. This speech was widely reported in newspapers across Britain, Ireland, North America, and Europe. Many people debated its ideas, and it helped increase support for evolutionary theories.

In 1864, Pope Pius IX declared that it was wrong to believe that human reason alone could explain everything or that the Bible’s teachings were incomplete. He warned that those who held these views would be condemned. These ideas conflicted with Tyndall’s belief in separating science and religion. However, Tyndall did not need to directly challenge the Pope in Britain. In Italy, scientists like Huxley and Darwin were honored, and the Italian government opposed the Pope’s authority. In Ireland, however, many people became more strongly religious and politically active during Tyndall’s lifetime. Between 1886 and 1893, Tyndall took part in debates about whether Ireland should have more independence. He opposed the Irish Home Rule Movement, believing that Catholic priests and the Catholic Church were central to the movement. He argued that giving the Catholic majority too much power would harm non-Catholics. He tried but failed to get Britain’s top scientific society to criticize the Home Rule proposal.

In his book Fragments of Science for Unscientific People, Tyndall wrote about why he thought prayers might not be effective. However, he was not openly against religion. Some people think Tyndall was an agnostic, meaning he believed the universe’s mysteries could not be fully understood. In 1867 and again in 1878, he said, “The mysteries of the universe remain unsolved, and we must accept our limits, whether we are priests, philosophers, or scientists.”

Personal life

John Tyndall married at the age of 55. His wife, Louisa Hamilton, was 30 years old and the daughter of Lord Claud Hamilton, a member of parliament. In 1877, the couple built a summer home in the Swiss Alps at Belalp. Before marriage, Tyndall lived in an apartment at the Royal Institution and continued to live there after his marriage until 1885, when he and Louisa moved to a house near Haslemere, which is 45 miles southwest of London. Their marriage was happy, and they had no children. Tyndall retired from the Royal Institution at age 66 due to health problems.

Tyndall became financially successful through the sale of his books and income from lectures. There is no evidence he owned patents. For many years, he earned modest income as a part-time scientific advisor to government-related organizations and gave some of the money to charity. His lecture tour in the United States in 1872 earned him a large amount of money, which he donated to support science in America. Later in life, he gave money to the Irish Unionist political cause. When he died, his total wealth was £22,122. At the same time, a police officer in London earned about £80 per year.

Death

In his later years, Tyndall used chloral hydrate to help with his trouble sleeping. When he was sick and unable to move, he died accidentally from too much of this medicine in 1893 at the age of 73. He was buried in Haslemere. His wife, Louisa, gave him the medicine that caused his death. Tyndall said to her, "My darling, you have killed your John," when he understood what had happened.

After his death, Louisa took control of Tyndall’s papers and became the person in charge of writing an official biography about him. However, she delayed the project and did not finish it before she died in 1940 at the age of 95. The biography was published in 1945, written by A. S. Eve and C. H. Creasey, who Louisa had approved to work on the project shortly before her death.

John Tyndall is honored with a memorial called the Tyndalldenkmal. It was built at an elevation of 2,340 meters (7,680 feet) on the mountain slopes above the village of Belalp, where he had a summer home. The memorial is visible from the Aletsch Glacier, which he studied.

Legacy and Commemorations

There is a school named after John Tyndall located in his home county of Carlow. Tyndall College is a school for both boys and girls that provides education after primary school. It is located on the Kilkenny Road in County Carlow and began operating in 2017 after combining two schools: Carlow Vocational School. The school was named to honor John Tyndall’s work in science and his connection to Irish history. Tyndall College is run by the Department of Education in the Republic of Ireland and serves students in County Carlow. It is a school that welcomes students of different religious backgrounds.

John Tyndall's books

• Tyndall, J. (1860), The glaciers of the Alps, a book about his travels and climbs, explaining how glaciers form and the science behind them, published in 1861 by Ticknor and Fields in Boston
• Tyndall, J. (1862), Mountaineering in 1861. A vacation tour, published by Longman, Green, Longman, and Roberts in London
• Tyndall, J. (1865), On Radiation: One Lecture (40 pages)
• Tyndall, J. (1868), Heat: A mode of motion, published in 1869 by D. Appleton in New York
• Tyndall, J. (1869), Natural Philosophy in Easy Lessons (180 pages) (a physics book for high school students)
• Tyndall, J. (1870), Faraday as a discoverer, published by Longmans, Green in London
• Tyndall, J. (1870), Three Scientific Addresses by Prof. John Tyndall (75 pages)
• Tyndall, J. (1870), Notes of a Course of Nine Lectures on Light (80 pages)
• Tyndall, J. (1870), Notes of a Course of Seven Lectures on Electrical Phenomena and Theories (50 pages)
• Tyndall, J. (1870), Researches on diamagnetism and magne-crystallic action: including the question of diamagnetic polarity (a compilation of 1850s research reports), published by Longmans, Green in London
• Tyndall, J. (1871), Hours of exercise in the Alps, published by Longmans, Green, and Co. in London
• Tyndall, J. (1871), Fragments of Science: A Series of Detached Essays, Lectures, and Reviews (1872 edition), published by Longmans, Green in London
• Tyndall, J. (1872), Contributions to Molecular Physics in the Domain of Radiant Heat (a compilation of 1860s research reports), published in 1873 by D. Appleton and Company in New York
• Tyndall, J. (1873), The forms of water in clouds & rivers, ice & glaciers, published by H. S. King & Co. in London
• Tyndall, J. (1873), Six Lectures on Light (290 pages)
• Tyndall, J. (1876), Lessons in Electricity at the Royal Institution (100 pages) (meant for high school students)
• Tyndall, J. (1878), Sound; delivered in eight lectures (1969 edition), published by Greenwood Press in New York
• Tyndall, J. (1882), Essays on the floating matter of the air, in relation to putrefaction and infection, published by D. Appleton in New York
• Tyndall, J. (1887), Light and electricity: notes of two courses of lectures before the Royal Institution of Great Britain, published by D. Appleton and Company in New York
• Tyndall, J. (1892), New Fragments (miscellaneous essays for a broad audience), published by D. Appleton in New York