John Tyndall: Darwin’s Defender

John Tyndall (1820 – 1893)

Born: Leighlinbridge, Co Carlow

It is Wednesday, 19th August 1874.  John Tyndall, from rural Co. Carlow, a scientific giant of the Victorian Age is about to get to his feet and make a headline-grabbing speech to his peers at the annual meeting of the British Association for the Advancement of Science (BAAS). This is a confident man – some might say belligerent – a brilliant communicator, whose public lectures on scientific topics in London are famous. However, if even the great Tyndall is nervous before this speech he has every right to be. He knows its importance and his enemies will be listening. These enemies are primarily the members of what might be called ‘the old guard’ of science. These are the gentlemen of science that for centuries have sought to accommodate religious views with their science. To them, there is no religious-scientific divide and no need for rancour or conflict between the two. The old guard was outraged when Tyndall and his pals at the notorious X-Club (more of them later) began a public campaign in support of the evolutionary theory of man as outlined by Charles Darwin in his book, Origin of the Species, published in 1859.  Darwin was not inclined to defend his theory in public, so others had to do it for him. Men like Zoologist Thomas Huxley argued that Darwin should at least be given a fair hearing, but Tyndall, in this speech plans to go further. He is well aware that his comments are likely to shock many that hear them, and read about them in newspaper reports all over the world. 

The old guard has long been worried about the emergence of a new breed of scientific men like Huxley and Tyndall, who now aged 54, holds the position of President of the prestigious BAAS. Tyndall’s role as the BAAS President provides him with a platform to outline his views and his agenda, as the President’s annual address was always reported with interest by members of the press. The old guard was right when they worried about Tyndall as he represents not just a threat to their outdated ideas, and methods, but also to their waning power base in science. In his speech, Tyndall plans to shake them further by demanding that religion, and superstitions of all kinds, as he sees it, be completely removed from the scientific arena. The reason why the sky is blue, why the Earth stays warm, and is full of life, or why there can be wild and seemingly random fluctuations between the Earth’s warm and cold periods: This can all be explained by rational scientific investigation, observation and experimentation, and the answers have nothing at all to do with Gods or divine intervention. Pointedly, he will deliver his unequivocal message in his native Ireland, in a city famous for the strength of its religious fervour – Belfast. He will further articulate the view that churchmen, most particularly the Catholic clergy, have had far too much influence over the education of young minds, and that the Catholic Church has stymied and stunted the development of science over many centuries. Tyndall’s speech will leave his audience gaping and be debated around the world. It will mark the opening salvo of a religion versus science conflict that continues to fester to this very day. 

The ‘X Club’

In a moment we will return to Belfast, and Tyndall’s famous address, but before we do so, it’s important to understand the context of his epic speech. To do that, we must look at the origins of the famous, or infamous to some, ‘X Club’ of 19th century British scientists, of which Tyndall was a leading member. The club, which was formed in November 1864, was made up of nine members, all linked by their “devotion to science, pure and free, untrammeled by religious dogmas”.  As well as a shared aim of resisting clerical interference in science, as they saw it, the men also wished to put science, and scientists, on a professional footing. 

Who made up the X-Club? The members were Thomas Huxley (Tyndall’s friend since they met in 1858 and the Club’s main initiator); John Tyndall; Edward Frankland (a chemist that taught school with Tyndall at Queenswood and went to Marburg University with him to take a PhD ); Thomas Archer Hirst (a mathematician and friend of Tyndall’s since the 1840s); Joseph Dalton Hooker (botanist and Charles Darwin’s closest friend) and George Busk (naval surgeon, zoologist and palaeontologist); William Spottiswoode (mathematician and physicist); John Lubbock (a banker that helped established archaeology as a science, and by far the youngest club member); and lastly Herbert Spencer (philosopher, biologist and the man credited with the phrase ‘survival of the fittest’ which he used in a paper he wrote after reading The Origin of the Species). 

The X-Club was made up of talented, ambitious men, who wished to challenge how science was run. In many ways, they were outsiders, like Tyndall, who was Irish, had been educated in an Irish national school, mixing with Catholics, and his family had modest financial means. He was also an artisan that that received a vocational education in drawing and surveying, and paid his own way to do a PhD. Anything that Tyndall achieved, like the other members of the Club, he had to work hard for and earn. This in itself was a challenge to the established order. 

Many of the grandees of British science, the ones that held leadership positions, and had done so for centuries, were a combination of wealthy amateurs, with the time to pursue their interest in studying science and nature, and churchmen. In contrast, the ‘X Club’ was made up of men were from the growing middle classes. These men regarded science as their profession, their livelihood, not just a hobby.  

Tensions between the forces of ‘old’ and ‘new’ science, for the control of British science, had been brewing since the early decades of the 19th century. The covert power struggle emerged into open view following the 1859 publication of Charles Darwin’s The Origin of the Species. The establishment expressed outrage with Darwin’s claims and attacked him at every opportunity. Darwin was not inclined to defend himself, so others stepped into the breach. Many of those who lept to Darwin’s defence – such as Tyndall and Huxley – were to later join the X-Club. 

The BAAS was then the most influential scientific body in Britain, and still is. Therefore, it was inevitable that a power struggle would break out for its control between the Darwin-supporting ‘X clubbers’ and the old grandees of science supported by the church. The X club emerged victorious from this struggle, which reached its epiphany in the early 1860s, but simmered for decades afterwards. 

By 1868, almost a decade after Darwin’s book was published, the X-Club had seized control of the BAAS. From 1868 and 1881, when the Club was at the height of its powers, five of its nine members held the Presidency of the BAAS. Thus, when Tyndall got to his feet in August 1874 to deliver his Presidential address to his peers, he was doing it from a position of strength. He knew his argument had won the day among his scientific peers, although enemies still lurked within. His main purpose was not to win over his fellow scientists, but to attack the enemies of the X-Club outside of the scientific community and win over public opinion. 

Belfast address 

Tyndall got to his feet, and began this talk. In a long and wide-ranging address, he describes the entire history of scientific thought in mankind as he saw it, and the way that its progress was impeded by the power of the Church. He describes how Galileo was compelled to swear on the bible that his ‘heliocentric theory’, which held that the Earth revolved around the Sun, was false, or be burnt alive. The Church’s oppression of science is a theme he brings up again and again. 

He attacked the theory of spontaneous generation of life – believed by many Christians in the 19th century, which held that life could simply burst into life. Tyndall had found a way to sterilize a surface, and kill all life. He used this technique to show that life could not simply grow from nothing on a sterile surface. This was a direct attack on the creationist view of how life arose. 

Finally, more than halfway through his long address, he got onto the main subject of his talk; Darwin, and the many reasons why he believed his ideas of the Origins of Man, rang true. Tyndall said that the theory fits with much modern scientific thinking, and that it is the result of years of painstakingly observations by a very thorough, and dedicated scientist. He said of Darwin: “He moves over the subject with the passionless strength of a glacier; and the grinding of the rocks is not always without a counterpart in the logical pulverization of the objector”. 

The conflict between the ‘new science’ and religion was a hot topic in the mid 1870s and had been every since Darwin’s ‘Origin’ was published. Many daily newspapers in Britain, Ireland, North America, and the European continent, carried a report of Tyndall’s address on their front pages. It caused such a stir that the opponents of Darwin felt obliged to respond – also in the newspapers. Tyndall, as Darwin’s most articulate defender, had reached a global audience. This case for ‘rational science’ had been made and heard all around the world. 


Without question, John Tyndall was one of Ireland’s greatest scientists. In fact, he was one of the greatest scientists of Victorian Britain and Ireland. His interests were vast, and his influence was huge. His fame was achieved at a time (1850s to the 1890s) when the United Kingdom of Britain and Ireland was the world’s undisputed superpower, and home to many brilliant scientific minds. Yet today Tyndall’s name hardly registers a blip with most Irish people. Why? The reason is simple; his family background and beliefs were unpalatable to the majority here. 

An insight into Tyndall’s political thinking on Ireland comes in an opinion piece he wrote for The Times of London on the 27th December 1890. In it, he describes priests and Catholicism as “the heart and soul” of the Home Rule movement. He says that placing the non-Catholic minority under the dominion of “the priestly horde” would be “an unspeakable crime”. He even tried, without success, to get the British Association for the Advancement of Science (BAAS), Britain’s leading scientific body, to denounce Home Rule as being against the interests of science. 

Tyndall was born in 1820 in Leighlinbridge co. Carlow, an area on the edge of ‘The Pale’ where for several centuries there had been cultural tensions between newcomers, mainly from Britain (termed ‘settlers’ by the Government, and ‘planters’ by the locals) and the indigenous people. Tyndall was part of the resented settler group, as his ancestors had arrived from Gloucestershire in the 17th century, not long after the ruthless Cromwellian conquest of Ireland. It is not hard to imagine, given all this, why Tyndall was airbrushed out of Irish history, despite his great achievements, particularly after Irish independence in 1922. 

The Tyndalls were Quakers. This meant they were part of a faith of dissenters that had broken away from the Protestant Church of England around the middle of the 17th century in an attempt to restore what they believed were the authentic practices of the early Christian church. Tyndall’s father, also called John, was an intelligent man, of modest means, an R.I.C. constable, who worked hard to afford the best possible education for his son John. ‘Father John’ was also, reportedly, fiercely anti-Catholic, and this, undoubtedly, had an influence on his son. John Junior’s mother, Sarah McAssey, was descended from wealthy local Catholic landowners, but it seems, her grandmother, Tyndall’s great-grandmother, was cut off from her inheritance by marrying a Quaker. He had one sister, Emma. 

In the 1820s, largely as a result of the campaign for Catholic Emancipation led by ‘The Liberator’ Daniel O’Connell, the Government in London decided to fund the world’s first state-supported school system. This was done in order to facilitate the education of children that were not members of the ‘established’ Church of Ireland. Tyndall, as a Quaker, was part of the first generation of Irish children, along with neighbouring Catholic children, to benefit from this new state school system. He attended the one-room Ballinabranna Mixed National School, which is located about halfway between the towns of Leighlinbridge and Carlow (the school is still in existence today, but larger, and home to roughly 150 pupils). 

‘Father John’ despite his anti-Catholic sentiments, was keen that his son attend Ballinabranna school, despite the fact that he would be mixing with Catholic children, as the teacher there, John Conwill, also a Catholic, and former hedge-school teacher, was a teacher of renown. He came under fierce pressure from his Protestant neighbours, including the rector of Leighlinbridge, Dean Barnard Boyle, not to send John jnr. to Ballinabranna. He resisted, and reportedly remarked memorably that “even if he was taught on the steps of the altar” he would send his son to Conwill. John was taught English, Logic, Book-Keeping, Drawing, Surveying and Mathematics and excelled at the latter two subjects. 

Youthful ambition  

Tyndall’s education certainly proved crucial to setting him on the right path, as directly from his leaving school, aged 19, he got a job in the Irish Ordnance Survey and moved to Youghal. There he remained for a few years, until he was chosen to join the more prestigious English survey and moved over to Preston.  

It is interesting to note that Tyndall became very unhappy in Preston for what he regarded as discrimination towards Irish assistants in the Survey office there. He was so unhappy, in fact, that he lodged a formal protest on behalf of his fellow Irishmen for the way in which the assistants were being exploited. He was soon regarded as a leader of malcontents, and this led to his dismissal in November 1843. Aged just 23, Tyndall’s showed he was prepared to fight for the rights of others, to take on powerful establishment forces, even if it meant losing his job. 

His next employment was as a railway surveyor on the West Yorkshire Line, during the height of ‘railway fever’. He did this for the next few years, and was making excellent money – something he was always good at throughout his life. However, in 1847, he left his lucrative surveying job, to the great surprise of his friends and family, to take up a teaching job at a progressive Quaker school called Queenswood College. This move showed that money was not his ‘God’ and that his true interests lay in mathematics, as well as the relatively new, at the time, science of physics, and engineering. He didn’t last long at Queenswood, as it didn’t satisfy his insatiable drive for knowledge, and to take his education one stage further, he left for Germany, in 1848, with a friend, Edward Frankland, who was the Superintendent of the Science Laboratory at Queenswood. They had both decided to attend Marburg University; a centre of modern scientific thinking, in order to attain a PhD. Tyndall excelled there and got his PhD in just two years.  The move to Germany was self-financed, and the two young men had to suffer some severe hardships in order to eat and have a roof over their heads while they studied. This is another example of how Tyndall was oblivious to material gain. 

After he finished his studies in Marburg in 1849, Tyndall began searching for an academic post in a university. He applied for positions, without success, in far flung places like Toronto, Sydney, as well as Cork and Galway. For the next few years he struggled to get his career moving, but a major turning point came in February 1853 when he was invited to give a Friday lecture at the famous Royal Institution of Great Britain in London, which had Michael Faraday at its head. His lecture hugely impressed everyone that heard it, including Faraday, and he was invited to give further lectures. Quickly, his lectures became famous for the way that Tyndall had with explaining difficult concepts to a non scientific audience. The crowds came to hear Tyndall, and his fame began to grow rapidly. A few short months later, in May, he was unanimously appointed as Professor of Natural Philosophy (Physics) in the Royal Institution. The agreement was that he was to provide nineteen public lectures per year, and would be paid a salary of £200. That was a substantial amount of money, considering that he was only committed to between – on average – one or two lectures per month, and the average salary for a clerk at the time was approximately £150 per annum. Tyndall was by now 33 years old, his career was finally on track and he was on his way to becoming an influential figure in science, whose fame extended beyond science.  

Royal society

Tyndall would spend the rest of his working life at the Royal Society, becoming its Director, taking over from Michael Faraday, when he died in 1867. He retired from the Society in 1887, aged 67, having spent 34 years working there. He left his mark on the institution, particularly in the way that he continued, and bettered, the efforts begun under Faraday to popularize science, and to make it intelligible to members of the public. Tyndall was, by all accounts, a gifted lecturer, and communicator, who used his oratorical skills, and experimental brilliance to hold an audience, and often leave them spellbound at the end. 

He could be reasonably called the first professional populariser of science, and certainly one of the first science writers ever to reach out to a broad audience. 

As well as lecturing to the public at the Royal Society, he went on tours overseas, to the USA, for example, and he wrote many books, explaining scientific concepts. His lectures always attracted a crowd, and his books were widely read. He was, thus, a wealthy man when he died and left a relative fortune (get the figure) in his will. 

Greenhouse gases 

After his appointment at the Royal Society, Tyndall was hungry to get to work. He wanted to understand the wonders of nature. By the late 1850s he had become focused on understanding the radiant heat of the Sun, and its relationship with the various gases present in the Earth’s atmosphere. These investigations would lead to, arguably, his greatest single contribution to science; the discovery of what we now call ‘greenhouse gases’ – gases that retain the heat of the Sun, keeping the Earth warm, and making life possible here through the ‘greenhouse effect’. 

Tyndall discovered that two gases present in tiny ‘trace’ concentrations in the atmosphere, were absolutely critical for life. These key gases were carbon dioxide (CO2) and water vapour, which between them only constitute less than two per cent of the gases in the atmosphere. Tyndall demonstrated that CO2 and water vapour could effectively absorb and hold on to the heat of the Sun, unlike far more common atmospheric gases such as nitrogen and oxygen, which make up more than 98 per cent of the gases in the atmosphere, but have no such ability. 

The importance of the finding was that without CO2 and water vapour, which are now called the ‘greenhouse gases’, the heat of the Sun would travel through the Earth’s atmosphere to the surface, where much of it would bounce back up, and travel unimpeded back out to space. Thus, none of the Sun’s precious heat would be trapped, and Earth would be nothing more than an icy, lifeless, lump of rock. These days, greenhouses gases have a negative connotation associated with relentless global warming, but without them, no life could exist here on Earth. 

Cleanrooms & blue skies 

Tyndall is credited with being the first to explain, and demonstrate why the sky is blue. In one of his most famous lectures, he set up an experiment that stunned his audience by artificially re-creating blue skies inside the lecture theatre of the Royal Society.  What he did first was to show how light, which appears white, normally travels in a straight line unless it is blocked, reflected or absorbed by something. That ‘something’ can either be fine particles in the atmosphere, such as dust, pollen, and even salt from the oceans. Or it can be atmospheric gases. 

The creation of the artificial sky inside required that some of the white light traveling in a straight line be absorbed and radiated. White light, of course, is composed of all the components of the rainbow when split into its various parts. 

Light travels in waves, and different wavelengths, which are defined by the interval between wave repetitions, produce different colours. Red, orange and yellow are produced by longer wavelengths, for example, and these tend to pass through the atmosphere unimpeded. However, the shorter wavelengths, which produce the colour blue, tend to be absorbed by atmospheric gases. The absorbed blue light then gets radiated or ‘scattered all over the sky, giving it its blue hue. 

Tyndall’s work inspired ‘Lord Rayleigh’ to develop a measurable, mathematical explanation of why the sky is blue. This became known as ‘Rayleigh scattering’. 

Two other significant developments arose from Tyndall’s work on light. One had to do with measuring whether air could be made free from bacteria and germs, and the other led to the development of test for whether it was possible that life could spontaneously arise, something that creationists believed then, and now. 

In numerous experiments in the early 1870s, Tyndall showed that ‘optically pure air’ was free of bacteria and germs. At around the same time, Louis Pasteur was postulating that living germs floating in the atmosphere were a cause of human and animal disease. Tyndall was able to demonstrate that foods when exposed after boiling to optically pure air remained unspoiled, whereas the same foods, when exposed to ordinary dust laden air, after boiling, swarmed with bacteria. 

Tyndall wanted to show all rational people that creationism was based on nothing but superstition, and was irrational and unscientific. This was the reason that debunking the spontaneous generation of life argument was very important to him. The main advocate of the spontaneous generation of life on Earth at the time was a London pathologist, Charlton Bastian, and Tyndall intended to prove him wrong. In 1877, Tyndall came up with a process of repeated heating, which he called discontinuous heating, which succeeded in sterilizing liquids containing the most resistant germs. This method would become known as ‘tyndallization’ in France, and ‘pasteurization’ in Britain. Tyndall then sterilized the inside of a box, left it for some time untouched, came back, unsealed it, and found no living thing residing inside. This was a simple proof that life could not arise out of nothing. 

Tyndall was the first to design experiments that ‘guided’ light, and he developed the forerunner to fibre optic cabling that is so crucial for high-speed internet communications in many advanced industries today. Also, his achievement in being the first to produce optically pure air, resonates to this day, as many of Ireland’s advanced manufacturing units, such as Intel in Leixlip, are dependent on cleanrooms, where air is ultra-clean, preventing even the tinniest of particles from contaminating the manufacturing process. Cleanrooms began with Tyndall. 

Private life 

Tyndall was what we would call today a ‘workaholic’ and his output, in terms of books and letters written, experimental work, and lectures is phenomenal. It is remarkable in that context that he succeeded in having a private life, but he did. In his twenties and thirties he had a number of relationships with women, but it was only in 1869, at the relatively advanced age of 49, that he made his first proposal of marriage – it was rejected. After that rebuttal, it appeared certain to Tyndall’s friends and family that he would remain a bachelor for life, yet he surprised them all when he announced he was to marry Louisa Charlotte five years later, aged 56. Louisa was from aristocratic stock, the daughter of Lord Claud Hamilton and Lady Elizabeth Proby, and 25 years his junior. Louisa, unlike Tyndall, was also a very committed Christian. Despite their differences, it appears that theirs was a very happy marriage. The couple didn’t have any children. 

Tyndall had become very interested in mountaineering after traveling to the Alps in his mid thirties to study the mechanical behaviour of glaciers. He became an excellent climber and achieved many ‘firsts’ in terms of being the first to reach various alpine summits. Being Tyndall, his mind was always working, and his observations of glaciers led to a brilliant book The Glaciers of the Alps (1860). 

In 1877, the couple built a summer cottage, which they went to every year, in Brig, in the Alps of southern Switzerland, not far from the Italian border. 

He had suffered from insomnia, and dyspepsia (stomach indigestion and upset) almost all his life, but these got worse as Tyndall got older, and now he also suffered from attacks of phlebitis (vein inflammation). Illness directly led to his retirement in 1887, aged 66. There was no pension in those days, and Tyndall was not, as we have said here before, independently wealthy, so it was fortunate for him that he amassed a great deal of wealth from his prolific book writing. 

The manner of his death was tragic and bizarre. As his health deteriorated in his seventies, Tyndall took magnesia at night, something considered beneficial for overall good health. However, on one particular occasion, his wife gave him an overdose of chloral hydrate, instead of magnesia. Chloral hydrate is a sedative drug that is also used as a chemical reagent. A reagent is a substance that is added to a system, such as a fluid, to cause a chemical reaction, or to determine whether a chemical reaction has occurred. The effect of chloral hydrate poisoning is to attack the central nervous system, leading to vomiting, stupor, coma and death. This is what caused Tyndall’s death on 4th December 1893, aged 73.  

Reportedly, Tyndall immediately realized what had happened, expressed sympathy for his wife’s plight, and said goodbye. An inquest followed, following which the distraught Louisa was absolved of all blame. She had devoted herself to Tyndall, acting as ‘personal assistant’ and nurse. After he died she spent years gathering information to write a biography of his life. The biography didn’t make it into print until 1945, just five years after Louisa’s death at the age of 95.