John Tyndall 1820 – 1893

John Tyndall FRS 1820 – 1893 was a prominent 19th century physicist.

John Tyndall was a friend of Thomas Carlyle, John Chapman, Charles Darwin, Hermann von Helmholtz, Thomas Henry Huxley, Edward Bulwer Lytton, Robert Owen, Herbert Spencer, Alfred Lord Tennyson, and James John Garth Wilkinson.

Thomas Carlyle evangelised homeopathy to John Tyndall, who knew many homeopaths and homeopathic supporters, including Thomas Henry Huxley, Edward Bulwer Lytton, and James John Garth Wilkinson.

John Tyndall was also a contributor to John Chapman’s Westminster Review, _to which many homeopathic supporters contributed. _

John Tyndall attended Spiritualist meetings with Thomas Henry Huxley, Edward Bulwer Lytton, and James John Garth Wilkinson, and he conducted several experiments on the phenomenon he observed there. John Tyndall also studied the influence of prayer on terminally ill people:

In 1872, John Tyndall, an English physician, suggested that the community pray for from 3 - 5 years for patients ill with fatal diseases to see if differences (could be determined)…

John Tyndall was a friend of Thomas Henry Huxley, with whom he ran the science section of the Westminster Review and formed a group of evolutionists who helped pave the way for Charles Darwin’s 1859 publication of The Origin of Species and gave it backing in the ensuing furore.

John Tyndall and Thomas Henry Huxley were also members of the Metaphysical Society, and also of the X Club: The members were: Thomas Henry Huxley, John Tyndall, J. D. Hooker, John Lubbock (banker, biologist and cousin of Charles Darwin), Herbert Spencer (social philosopher and sub-editor of the Economist), William Spottiswoode (mathematician and the Queen’s Printer), Thomas Hirst (Professor of Physics at University College London), Edward Frankland (the new Professor of Chemistry at the Royal Institution) and George Busk, zoologist and palaeontologist (formerly surgeon for HMS Dreadnought). All except Herbert Spencer were Fellows of the Royal Society.

There were also some quite significant X Club satellites such as William Flower and George Rolleston, (Thomas Henry Huxley protegées), and liberal clergyman Arthur Stanley, the Dean of Westminster. Guests such as Charles Darwin and Hermann von Helmholtz were entertained from time to time.

http://en.wikipedia.org/wiki/John_Tyndall [Tyndall was born in Leighlinbridge, County Carlow, Ireland. His father was a local police constable and small landowner, descended from Gloucestershire emigrants who settled in southeast Ireland around

1670. ](http://en.wikipedia.org/wiki/John_Tyndall)

Tyndall attended the local schools in County Carlow until his late teens, and was probably an assistant teacher near the end of his time there. Subjects learned at school notably included technical drawing and mathematics with some applications of those subjects to land surveying.

He was hired as a draftsman by the government’s land surveying & mapping agency in Ireland in his late teens in 1839, and moved to work for the same agency in England in 1842.

In the decade of the 1840s, a railroad building boom was in progress, and Tyndall’s land surveying experience was valuable and in demand by the railroad companies. Between 1844 and 1847, he was lucratively employed in railroad construction planning.

In 1847, Tyndall opted to become a mathematics teacher at Queenwood College in Hampshire, an experimental school founded by the industrialist and social philosopher Robert Owen. He had met Robert Owen more than once and perhaps opted to work at Queenwood under Robert Owen’s influence.

Recalling this period later Tyndall wrote: “the desire to grow intellectually did not forsake me; and, when railway work slackened, I accepted in 1847 a post as master in Queenwood College.”However, he soon became dissatisfied with Queenwood.

Another recently arrived young teacher at Queenwood was Edward Frankland, who had previously worked as a laboratory assistant for the British Geological Survey. Edward Frankland and Tyndall became good friends. Together they decided to go to Germany to further their education in science. (The German universities were regarded as best in the world in chemistry and physics at the time. British universities were still focused on classics and mathematics and not science).

The pair moved to Germany in 1848 and studied at the University of Marburg, where Robert Bunsen was an influential teacher. Probably more influential for Tyndall at Marburg was Professor Hermann Knoblauch, with whom Tyndall maintained communications by letter for many years afterwards.

Tyndall’s Marburg dissertation was a mathematical analysis of screw surfaces in 1850 (under Friedrich Ludwig Stegmann). He stayed at Marburg for a further year doing research on magnetism with Hermann Knoblauch, including some months’ visit at the laboratory of Hermann Knoblauch’s main teacher, Gustav Magnus in Berlin.

Tyndall returned to England in 1851 with a first rate education in experimental science. It is clear today that Robert Bunsen and Gustav Magnus were among the very best experimental science instructors of the era.

Tyndall’s early original work in physical science was his experiments on magnetism and diamagnetic polarity, on which he worked from 1850 to

1856. His two most influential reports were the first two, co-authored with Hermann Knoblauch. One of them was entitled Second memoir on the magneto-optic properties of crystals, and the relation of magnetism and diamagnetism to molecular arrangement, dated May 1850. The two described an inspired experiment, with an inspired interpretation. These and other magnetic investigations very soon made Tyndall known among the leading scientists of the day.

In June 1852, he was elected a Fellow of the Royal Society. In his search for a suitable research appointment, he was able to ask the longtime editor of the leading German physics journal (Poggendorff) and other prominent men to write testimonials on his behalf.

In June 1853, Tyndall attained the prestigious appointment of Professor of Natural Philosophy at the Royal Institution, due in no small part to the esteem his work had garnered from Michael Faraday, then the leader of magnetic investigations at the Royal Institution. Tyndall remained at the Royal Institution for the rest of his career.

Beginning in the late 1850s, Tyndall mostly studied air, the earth’s atmosphere, and the physics of gasses, and his original research results included the following:

• Tyndall explained atmospheric heat in terms of the capacities of various gases to absorb (and transmit) radiant heat, a.k.a. infrared radiation. His measuring device, which used thermopile technology, was a significant early step in the history of absorption spectroscopy. He measured the infrared absorptive powers of the gases nitrogen, oxygen, water vapour, carbon dioxide, ozone, hydrocarbons, etc. He concluded that water vapour is the strongest absorber of heat in the atmosphere and is the principal gas controlling air temperature. Heat absorption by the bulk of the other gases is negligible. Prior to Tyndall it was widely surmised, but he was first to prove, that the earth’s atmosphere has a Greenhouse Effect. The sun’s energy arrives on the ground as visible light mostly, and returns back up from the ground as infrared energy mostly, and he showed that water vapor and some other atmospheric constituents substantially absorb infrared energy, hindering it from radiating back up to outer space.

• He contributed to establishing, as he put it in one of his tutorials, “the identity of light and radiant heat” where “identity” means alike in every way.He consolidated and enhanced James David Forbes and Hermann Knoblauch’s experiments demonstrating that the principal properties of visible light can be reproduced for radiant heat, namely reflection, refraction, diffraction, polarization, depolarization, double refraction, and rotation in a magnetic field (Faraday effect). He also converted radiant heat into visible light and coined the word ”calorescence” for that conversion. He referred to radiant heat as “obscure radiation”, “dark waves” or “ultra-red undulations”, as the word “infrared” didn’t start coming into use until the 1880s. Among his key laboratory tools were substances that are transparent to infrared and non-transparent to visible light; or vice versa. (Tyndall’s main published research reports about radiant heat were republished as a 450-page collection in 1872. The collection contains more than 200 mentions of the name Professor Magnus. Tyndall and Magnus closely studied each other’s radiant heat research during the 1860s.)

• In the investigations on radiant heat it had been necessary to use air from which all traces of floating dust and other particulates had been removed. A sensitive way to detect particulates is to bathe the air with intense light. The scattering of light by particulate impurities in air or other gasses is known today as the Tyndall effect, also known today as Rayleigh scattering due to a later analysis by Rayleigh. In studying this scattering Tyndall developed the nephelometer and other precision instruments. Particulates suspended in air are visible to the naked eye in a darkened room with sunlight coming through a crack in the curtains. Mostly visibly that’s light reflecting off large particulates which is not the same as light scattering off small particulates. But with dark background illumination and customized light beams, and without microscopes, very low concentrations of particulates far below the threshold of visibility become visible and quantifiable because of light scattering. When combined with microscopes, the result is the ultramicroscope, which was developed later by others. Tyndall is the founder of this line of scientific instruments, which are based on exploiting the Tyndall effect.

• In the lab he came up with a simple way to obtain “optically pure” air. Namely, he coated the inside walls of a box with glycerin, which is a sticky syrup. He discovered that after a few days’ wait, the air inside the sealed box was entirely particulate-free under examination with light beams, because the various floating-matter particulates had ended up getting stuck to the sticky walls. There were no signs of floating micro-organisms in the optically pure air. He compared what happened when he let heat-sterilized meats sit in such pure air, and in ordinary air. The meats in the pure air remained “sweet” (as he said) to smell and taste after many months of sitting, while the ones in ordinary air started to become putrid after a few days. These demonstrations extended Louis Pasteur’s earlier demonstrations that the presence of micro-organisms (“germs”) is a precondition for biomass decomposition. However, the next year (1876) some repeats of the exercise resulted in a surprising failure to reproduce it. From this he was led to find viable bacterial spores in heat-sterilized foods. The foods had been contaminated with dry bacterial spores from hay in the lab, he found out. All bacteria are killed by boiling but they have spores that can survive boiling, he correctly contended, citing research by Ferdinand Cohn. At the time this affirmed the ”germ theory” against a number of critics whose experimental results had been defective from the same cause. And he devised a method of killing the spores that came to be known as ”Tyndallization”. During the 1870s Pasteur and Tyndall were in frequent communication.

• During the 1860s and 1870s he published research reports and a book about sound propagation in air, and was a chief participant in a large-scale British project that developed a better foghorn. In laboratory demonstrations motivated by foghorn issues, he established that sound is partially reflected (i.e. partially bounced back like an echo) at the location where an air mass of one temperature meets another air mass of a different temperature; and more generally when a body of air contains two or more separate air masses of different densities or temperatures, the sound travels poorly because of reflections occurring at the interfaces between the air masses, and very poorly when many such interfaces are present. He then argued, though inconclusively, that this is the usual main reason why the same distant sound (e.g. foghorn) can be heard stronger or fainter on different days or at different times of day.

• He was the first to observe and report the phenomenon of Thermophoresis (1870). (Tyndall simply reported it, without explaining it. He spotted it in light beams while studying the Tyndall Effect. Later, as with the Tyndall Effect itself, it was further understood by John Strutt, a.k.a. Lord Rayleigh, who succeeded to Tyndall’s position at the Royal Institution upon Tyndall’s retirement).

• He was the first to show that ozone is an oxygen cluster.

• He is credited with the first ever atmospheric pollution measurements using infrared and scattering measurement instruments to monitor a city’s air quality (in London).

• Invented a better fireman’s respirator, a hood that filtered smoke and noxious gas from air.

As an indicator of his lifetime research output, an index of 19th century scientific research journals has Tyndall as author of 145 papers.

Tyndall was an experimenter and laboratory apparatus builder, not an abstract model builder. But he did attempt to extend his studies on the heat-absorptive power of gases into a research program about molecules.

That is one of the underlying agendas of his 1872 book Contributions to Molecular Physics in the Domain of Radiant Heat. It is also evident in the spirit of his widely read 1863 book Heat Considered as a Mode of Motion.

Besides heat, he also saw phenomena of magnetism and sound propagation as reducible to molecular behaviors. Invisible molecular behaviors were the ultimate substrate of all physical activity.

With this mindset, and his experiments, he outlined an account whereby differing types of molecules have differing absorptions of infrared (or other) radiation because their molecular structures give them differing oscillating resonances. He’d gotten into the oscillating resonances idea because he’d seen that any one type of molecule has differing absorptions at differing wavelengths.

He’d also seen that the absorption behavior of molecules is quite different from that of the atoms composing the molecules - for example nitric oxide (NO) absorbed more than a thousand times more infrared radiation than either nitrogen or oxygen. He also took pains to show that the vapor form of various molecules (such as H2O) has the same absorptive powers as the liquid form. Tyndall’s promotion of the molecular mindset, and his efforts to experimentally expose what molecules are, is discussed in “John Tyndall, The Rhetorician Of Molecularity”.

In his lectures at the Royal Institution Tyndall put a great value on

• and was talented at producing - lively, visible demonstrations of physics concepts. In one lecture, published later in one of his books, Tyndall demonstrated the propagation of light down through a stream of falling water via total internal reflection of the light. It was referred to as the “light fountain”.

It is historically significant today because it demonstrates the scientific foundation for modern fiber optic technology. During second half of the 20th century Tyndall was usually credited with being the first to make this demonstration. However, Jean Daniel Colladon published a report of it in Comptes Rendus in 1842, and there’s some suggestive evidence that Tyndall’s knowledge of it came ultimately from Jean Daniel Colladon and no evidence that Tyndall claimed to have originated it himself.

Tyndall was a pioneering mountain climber and distinguished member of the London based Alpine Club. He visited the Alps almost every summer from 1856 onward, was a member of the very first mountaineering team to reach the top of the Weisshorn (1861), and led one of the early teams to reach the top of the Matterhorn (1868). He summited Mont Blanc and Monte Rosa several times.

In the Alps, Tyndall studied glaciers, and especially glacier motion. His views on glacial flow brought him into dispute with others, particularly James David Forbes and James Thomson. It was known that glaciers moved, but the mechanism for this action was uncertain.

Some thought they slid like solids, others that they flowed like viscous liquids, others that they crawled by alternate thermal expansion and contraction, or by fracture and regelation. Tyndall believe that regelation, discovered by Michael Faraday, played a key role. James David Forbes didn’t see regelation in the same way.

Complicating the debate, a disagreement arose publicly over who deserved to get investigator credit for what. Articulate friends of James David Forbes (as well as James David Forbes himself) thought that James David Forbes should get the credit for most of the good science. Whereas Tyndall thought the credit should be distributed more widely.

Tyndall commented: “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 Jean Louis Rodolphe Agassiz and James David Forbes; the proof of the retardation of the bed belongs to James David Forbes alone; while the discovery of the locus of the point of maximum motion belongs, I suppose, to me.”

When James David Forbes and Tyndall were in the grave, their disagreement was continued by their respective official biographers. Everyone tried to be reasonable, but agreement wasn’t attained. More disappointingly, aspects of glacier motion remained not understood or not proved.

Tyndall Glacier in Chile is named after John Tyndall, as is Mount Tyndall in California and Mount Tyndall in Tasmania.

Besides a scientist, John Tyndall was a science teacher and evangelist for the cause of science. He spent a significant amount of his time disseminating science to the general public - contributing over the years to science columns in popular middle class periodicals such as the Athenaeum and the Saturday Review in the UK, and Popular Science Monthly in the US; and giving hundreds of public lectures to non specialist audiences at the Royal Institution.

When he went on a public lecture tour in the US in 1872, large crowds paid fees to hear him lecture about the nature of light. A book devoted to contemporary celebrities published in 1878 in London had this to say: “Following the precedent set by Michael Faraday, Professor Tyndall has succeeded not only in original investigation and in teaching science soundly and accurately, but in making it attractive…

When he lectures at the Royal Institution the theatre is crowded.”Tyndall said of the occupation of teacher “I do not know a higher, nobler, and more blessed calling.”His greatest audience was gained ultimately thorough his books, most of which were not written for experts or specialists. He published 17 science books.From the mid 1860s on, he was one of the world’s most famous living physicists, due firstly to his skill and industry as a tutorialist. Most of his books were also translated into Germanand Frenchwith his main tutorials staying in print in those languages for decades…

The majority of the progressive and innovative British physicists of Tyndall’s generation were conservative and orthodox on matters of religion. That includes for example James Joule, Balfour Stewart, James Clerk Maxwell, George Gabriel Stokes and William Thomson -  all names investigating heat or light contemporaneously with Tyndall.

Tyndall, however, was a member of a club that vocally supported Charles Darwin’s theory of evolution and sought to establish a barrier, or separation, between religion and science. The anatomist Thomas Henry Huxley was the most prominent member of this club. Tyndall first met Thomas Henry Huxley in 1851 and the two had a lifelong friendship. Chemist Edward Frankland and mathematician Thomas Archer Hirst, both of whom Tyndall had known since before going to university in Germany, were members too. Others included the political philosopher Herbert Spencer. See X-Club.

Though not nearly so prominent as Thomas Henry Huxley in controversy over theological problems, Tyndall played his part in communicating to the educated public the virtues of having a clear separation between science (rationality & knowledge) and religion (faith & spirituality). As the elected president of the British Association for the Advancement of Science in 1874 he gave a long keynote speech at the Association’s annual meeting held that year in Belfast.

The speech gave a favorable account of the history of evolutionary theories, mentioning Charles Darwin’s name favorably 19 times, and concluded by asserting that religious sentiment should not be permitted to “intrude on the region of knowledge, over which it holds no command”.

This was a hot topic. The newspapers carried the report of it on their front pages - in the British Isles, North America, even the European Continent - and many critiques of it appeared soon after. The attention and debate, on the whole, increased the friends of Tyndall’s philosophical position.

In several essays included in his book Fragments of Science for Unscientific People: A Series of Detached Essays, Lectures, and Reviews Tyndall attempted to dissuade people from the belief in miracles and the effectiveness of prayers. At the same time, though, he was not broadly anti religious, and his writings leave no straightforward evidence that he was not a Christian or at least a Deist.

In Rome the Pope in 1864 decreed that it was an error that “reason is the ultimate standard by which man can and ought to arrive at knowledge” and an error that “divine revelation is imperfect” in the Bible - and anyone maintaining those errors was to be “anathematized”

• and in 1888 decreed as follows: “The fundamental doctrine of rationalism is the supremacy of the human reason, which, refusing due submission to the divine and eternal reason, proclaims its own independence… A doctrine of such character is most hurtful both to individuals and to the State… It follows that it is quite unlawful to demand, to defend, or to grant, unconditional [or promiscuous] freedom of thought, speech, writing, or religion.”

Those principles and Tyndall’s principles were profound enemies. Luckily for Tyndall he didn’t need to get into a contest with them, in Britain, nor in most other parts of the world. Even in Italy, Thomas Henry Huxley and Charles Darwin were awarded honorary medals and most of the Italian governing class was hostile to the papacy.

But in Ireland during Tyndall’s lifetime the majority of the population grew increasingly doctrinaire and vigorous in its Roman Catholicism and also grew stronger politically. It would’ve been a waste of everybody’s time for Tyndall to debate the Irish Catholics, but he was active in the debate in England about whether to give the Catholics of Ireland more freedom to go their own way.

Like the great majority of Irish born scientists of the 19th century he opposed the Irish Home Rule movement. He had ardent views about it, which were published in newspapers and pamphlets. For example in an opinion piece in The Times on 27 Dec 1890 he saw priests and Catholicism as “the heart and soul of this movement” and wrote that placing the non Catholic minority under the dominion of “the priestly horde” would be “an unspeakable crime”. He tried unsuccessfully to get the UK’s premier scientific society to denounce the Irish Home Rule proposal as contrary to the interests of science.

Tyndall did not marry until age 55. His bride, Louisa Hamilton, who he had first met in the Alps, was the 30 year old daughter of Lord Claud Hamilton, Member of Parliament (representing the Ulster constituency of Tyrone for the Conservative Party). The following year, 1877, they built a summer chalet at Belalp in the Swiss Alps.

Before getting married Tyndall had been living for many years in an upstairs apartment at the Royal Institution and continued to live there after marriage until 1885 when a move was made to a house near Haslemere 45 miles southwest of London. The marriage was a happy one and without children. He retired from the Royal Institution at age 66 having complaints of ill health.

Tyndall became financially well off from sales of his popular books and fees from his lectures (but no evidence he owned commercial patents). His successful lecture tour of the United States in 1872 brought him a substantial amount of dollars, all of which he promptly donated to a trustee for fostering science in America.Late in life his money donations went most visibly to the Irish Unionist political cause.

In his last years Tyndall often took chloral hydrate to treat his insomnia. He died from an accidental overdose of this drug at age 73, and was buried at Haslemere. Afterwards, Tyndall’s wife took possession of his papers and assigned herself as supervisor of an official biography of him. She dragged her feet on the project, however, and it was still unfinished when she died in 1940 aged 95.The book eventually appeared in 1945, written by A. S. Eve and C. H. Creasey, who Louisa Tyndall had authorized shortly before her death.