John Tyndall

John Tyndall

Overview
John Tyndall FRS (2 August 1820 – 4 December 1893) was a prominent Irish
Irish
Irish may refer to:*Irish cuisine* Ireland, an island in north-western Europe, on which are located:** Northern Ireland, a constituent country of the United Kingdom** Republic of Ireland, a sovereign state...

 19th century physicist. His initial scientific fame arose in the 1850s from his study of diamagnetism
Diamagnetism
Diamagnetism is the property of an object which causes it to create a magnetic field in opposition to an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus changing the...

. Later he studied thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....

, and produced a number of discoveries about processes in the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

. Tyndall published seventeen books, which brought state-of-the-art 19th century experimental physics
Experimental physics
Within the field of physics, experimental physics is the category of disciplines and sub-disciplines concerned with the observation of physical phenomena in order to gather data about the universe...

 to a wider audience. From 1853 to 1887 he was professor of physics at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 of Great Britain, where he became the successor to positions held by Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

.

Tyndall was born in Leighlinbridge
Leighlinbridge
Leighlinbridge is a village on the River Barrow in County Carlow, Ireland. The N9 National primary route once passed through the village, which was by-passed in the 1980s. It now lies on the R705 regional road....

, County Carlow
County Carlow
County Carlow is a county in Ireland. It is part of the South-East Region and is also located in the province of Leinster. It is named after the town of Carlow, which lies on the River Barrow. Carlow County Council is the local authority for the county...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

.
Discussion
Ask a question about 'John Tyndall'
Start a new discussion about 'John Tyndall'
Answer questions from other users
Full Discussion Forum
 
Quotations

Knowledge once gained casts a faint light beyond its own immediate boundaries.

On the Methods and Tendencies of Physical Investigation, p. 7

Life is a wave, which in no two consecutive moments of its existence is composed of the same particles.

Vitality

The mind of man may be compared to a musical instrument with a certain range of notes, beyond which in both directions we have an infinitude of silence.

Matter and Force

The brightest flashes in the world of thought are incomplete until they have been proved to have their counterparts in the world of fact.

Scientific Materialism

It is as fatal as it is cowardly to blink facts because they are not to our taste.

Science and Man

Superstition may be defined as constructive religion which has grown incongruous with intelligence.

Science and Man

Religious feeling is as much a verity as any other part of human consciousness; and against it, on the subjective side, the waves of science beat in vain.

Professor Rudolf Virchow|Virchow and Evolution
Encyclopedia
John Tyndall FRS (2 August 1820 – 4 December 1893) was a prominent Irish
Irish
Irish may refer to:*Irish cuisine* Ireland, an island in north-western Europe, on which are located:** Northern Ireland, a constituent country of the United Kingdom** Republic of Ireland, a sovereign state...

 19th century physicist. His initial scientific fame arose in the 1850s from his study of diamagnetism
Diamagnetism
Diamagnetism is the property of an object which causes it to create a magnetic field in opposition to an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus changing the...

. Later he studied thermal radiation
Thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....

, and produced a number of discoveries about processes in the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

. Tyndall published seventeen books, which brought state-of-the-art 19th century experimental physics
Experimental physics
Within the field of physics, experimental physics is the category of disciplines and sub-disciplines concerned with the observation of physical phenomena in order to gather data about the universe...

 to a wider audience. From 1853 to 1887 he was professor of physics at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 of Great Britain, where he became the successor to positions held by Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

.

Early years and education


Tyndall was born in Leighlinbridge
Leighlinbridge
Leighlinbridge is a village on the River Barrow in County Carlow, Ireland. The N9 National primary route once passed through the village, which was by-passed in the 1980s. It now lies on the R705 regional road....

, County Carlow
County Carlow
County Carlow is a county in Ireland. It is part of the South-East Region and is also located in the province of Leinster. It is named after the town of Carlow, which lies on the River Barrow. Carlow County Council is the local authority for the county...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. His father was a local police constable, descended from Gloucestershire
Gloucestershire
Gloucestershire is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn, and the entire Forest of Dean....

 emigrants who settled in southeast Ireland around 1670. 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
Technical drawing
Technical drawing, also known as drafting or draughting, is the act and discipline of composing plans that visually communicate how something functions or has to be constructed.Drafting is the language of industry....

 and mathematics with some applications of those subjects to land surveying. He was hired as a draftsman
Technical drawing
Technical drawing, also known as drafting or draughting, is the act and discipline of composing plans that visually communicate how something functions or has to be constructed.Drafting is the language of industry....

 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 railway companies. Between 1844 and 1847, he was lucratively employed in railway construction planning.

In 1847 Tyndall opted to become a mathematics and surveying teacher at a boarding school in Hampshire
Hampshire
Hampshire is a county on the southern coast of England in the United Kingdom. The county town of Hampshire is Winchester, a historic cathedral city that was once the capital of England. Hampshire is notable for housing the original birthplaces of the Royal Navy, British Army, and Royal Air Force...

. Recalling this decision later, he 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." Another recently arrived young teacher at Queenwood was Edward Frankland
Edward Frankland
Sir Edward Frankland, KCB, FRS was a chemist, one of the foremost of his day. He was an expert in water quality and analysis, and originated the concept of combining power, or valence, in chemistry. He was also one of the originators of organometallic chemistry.-Biography:Edward Frankland was born...

, who had previously worked as a chemical laboratory assistant for the British Geological Survey. Frankland and Tyndall became good friends. On the strength of Frankland's prior knowledge, they decided to go to Germany to further their education in science. Among other things, Frankland knew that certain German universities were ahead of any in Britain in experimental chemistry and physics. (British universities were still focused on classics and mathematics and not laboratory science.) The pair moved to Germany in summer 1848 and enrolled at the University of Marburg, where Robert Bunsen
Robert Bunsen
Robert Wilhelm Eberhard Bunsen was a German chemist. He investigated emission spectra of heated elements, and discovered caesium and rubidium with Gustav Kirchhoff. Bunsen developed several gas-analytical methods, was a pioneer in photochemistry, and did early work in the field of organoarsenic...

 was an influential teacher. Tyndall studied under Bunsen for two years. Perhaps 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 Knoblauch, including some months' visit at the Berlin laboratory of Knoblauch's main teacher, Heinrich Gustav Magnus. It is clear today that Bunsen and Magnus were among the very best experimental science instructors of the era. Thus, when Tyndall returned to live in England in summer 1851, he probably had as good an education in experimental science as anyone in England.

Early scientific work


Tyndall's early original work in physics was his experiments on magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...

 and diamagnetic polarity, on which he worked from 1850 to 1856. His two most influential reports were the first two, co-authored with Knoblauch. One of them was entitled "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. He was elected a Fellow of the Royal Society in 1852. In his search for a suitable research appointment, he was able to ask the longtime editor of the leading German physics journal (Poggendorff
Johann Christian Poggendorff
Johann Christian Poggendorff , was a German physicist born in Hamburg.By far the greater and more important part of his work related to electricity and magnetism. Poggendorff is known for his electrostatic motor which is analogous to Wilhelm Holtz's electrostatic machine...

) and other prominent men to write testimonials on his behalf. In 1853, he attained the prestigious appointment of Professor of Natural Philosophy
Natural philosophy
Natural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...

 (Physics) at the Royal Institution in London, due in no small part to the esteem his work had garnered from Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

, the leader of magnetic investigations at the Royal Institution.

Main scientific work


Beginning in the late 1850s, Tyndall studied the action of radiant energy
Radiant energy
Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy may be calculated by integrating radiant flux with respect to time and, like all forms of energy, its SI unit is the joule. The term is used particularly when radiation is emitted by a source into the...

 on the constituents of air, and it led him onto several lines of inquiry, and his original research results included the following:
  • Tyndall explained the heat in the Earth's atmosphere in terms of the capacities of the various gases in the air to absorb
    Absorption (electromagnetic radiation)
    In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is...

     radiant heat, a.k.a. infrared radiation. His measuring device, which used thermopile
    Thermopile
    A thermopile is an electronic device that converts thermal energy into electrical energy. It is composed of several thermocouples connected usually in series or, less commonly, in parallel....

     technology, is an early landmark in the history of absorption spectroscopy
    Absorption spectroscopy
    Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a...

     of gases. He was the first to correctly measure the relative infrared absorptive powers of the gases nitrogen, oxygen, water vapour, carbon dioxide, ozone, methane, etc. He concluded that water vapour is the strongest absorber of radiant heat in the atmosphere and is the principal gas controlling air temperature. Absorption by the other gases is not negligible but relatively small. Prior to Tyndall it was widely surmised that the Earth's atmosphere has a Greenhouse Effect
    Greenhouse effect
    The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...

    , but he was the first to prove it. The proof was that water vapor strongly absorbed infrared radiation.

  • He devised demonstrations that advanced the question of how radiant heat is absorbed and emitted at the molecular level. He appears to be the first person to have demonstrated experimentally that emission of heat in chemical reactions has its physical origination within the newly created molecules (1864). He produced instructive demonstrations involving what he called calorescence
    Calorescence
    Calorescence is a word for when matter absorbs infrared radiant energy and emits visible radiant energy in its place. For example, some kinds of flammable gas give off large amounts of radiant heat and very little visible light when burning, and if a piece of metal is placed into such a flame, the...

    , which is the conversion of infrared into visible light at the molecular level. Among his key laboratory tools were substances that are transparent to infrared and opaque to visible light; or vice versa. He usually referred to infrared as "radiant heat", and sometimes as "ultra-red undulations", as the word "infrared" did not start coming into use until the 1880s. His main published reports of the 1860s were republished as a 450-page collection in 1872 under the title Contributions to Molecular Physics in the Domain of Radiant Heat.

  • In the investigations on radiant heat in air it had been necessary to use air from which all traces of floating dust and other particulates
    Particulates
    Particulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...

     had been removed. A very sensitive way to detect particulates is to bathe the air with intense light. The scattering of light by particulate impurities in air and other gases, and in liquids, is known today as the Tyndall Effect or Tyndall Scattering
    Tyndall effect
    The Tyndall effect, also known as Tyndall scattering, is light scattering by particles in a colloid or particles in a fine suspension. It is named after the 19th century physicist John Tyndall. It is similar to Rayleigh scattering, in that the intensity of the scattered light depends on the fourth...

    . In studying this scattering during the late 1860s Tyndall was a beneficiary of recent improvements in electric-powered lights. He also had the use of good light concentrators. He developed the nephelometer
    Nephelometer
    A nephelometer is a stationary or portable instrument for measuring suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam and a light detector set to one side of the source beam. Particle density is then a function of the...

     and turbidimeter
    Turbidity
    Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....

     and similar instruments that show properties of aerosols and colloids through concentrated light beams. 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
    Scattering
    Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of...

     off small particulates. But with dark background illumination and customized light beams, and without microscopes, very low concentrations of particulates very far below the threshold of visibility become visible and quantifiable because of light scattering. When combined with microscopes, the result is the ultramicroscope
    Ultramicroscope
    An ultramicroscope is a system of illumination for viewing tiny particles. When the diameter of a particle is below or near the wavelength of light , the particle cannot be seen in a light microscope with the usual method of illumination. The ultramicroscope system is based on light scattering, not...

    , which was developed later by others. Tyndall is the founder of this line of instruments, which are based on exploiting the Tyndall effect.

  • In the lab he came up with a simple way to obtain "optically pure" air. 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 (the box had glass windows for the purpose). The various floating-matter particulates had all ended up getting stuck to the walls or settling on the sticky floor. There were no signs of floating micro-organisms ("germs") in the optically pure air. He compared what happened when he let sterilized meat-broths sit in such pure air, and in ordinary air. The broths were sterilized beforehand by boiling. The broths sitting in the optically 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. This demonstration extended Louis Pasteur
    Louis Pasteur
    Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...

    's earlier demonstrations that the presence of micro-organisms 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 supposedly heat-sterilized foods. The foods had been contaminated with dry bacterial spores from hay
    Hay
    Hay is grass, legumes or other herbaceous plants that have been cut, dried, and stored for use as animal fodder, particularly for grazing livestock such as cattle, horses, goats, and sheep. Hay is also fed to pets such as rabbits and guinea pigs...

     in the lab, he found out. All bacteria are killed by boiling but they have a spore form that can survive boiling, he correctly contended, citing research by Ferdinand Cohn
    Ferdinand Cohn
    Ferdinand Julius Cohn was a German biologist.Cohn was born in Breslau in the Prussian Province of Silesia. At the age of 10 he suffered hearing impairment. He received a degree in botany in 1847 at the age of nineteen at the University of Berlin. He was a teacher and researcher at University of...

    . Tyndall found a way to eradicate the bacterial spores that came to be known as "Tyndallization
    Tyndallization
    Tyndallization is an old process for sterilizing food. It is still occasionally used.A simple, effective, modern sterilizing method is to heat the substance being sterilized to 121°C for 15 minutes in a pressure cooker...

    ". At the time, it affirmed the "germ theory" against a number of critics whose experimental results had been defective from the same cause. During the mid-1870s Pasteur and Tyndall were in frequent communication.

  • He was the first to observe and report the phenomenon of thermophoresis
    Thermophoresis
    Thermophoresis, thermodiffusion, or Soret effect , is a phenomenon observed when a mixture of two or more types of motile particles are subjected to the force of a temperature gradient and the different types of particles respond to it differently. The term "Soret effect" normally means...

     in aerosols. He spotted it surrounding hot objects while investigating the Tyndall Effect with focused lightbeams in a dark room. He devised a better way to demonstrate it, and then simply reported it (1870), without investigating the physics of it in depth.



  • In radiant-heat experiments that called for much laboratory expertise in the early 1860s, he showed for a variety of readily vaporizable liquids that, molecule for molecule, the vapor form and the liquid form have essentially the same power to absorb radiant heat. (In modern experiments using narrow-band spectra, some relatively small differences are found that Tyndall's equipment was unable to get at; see e.g. absorption spectrum of H2O
    Water absorption
    During the transmission of electromagnetic radiation through a medium containing water molecules, portions of the electromagnetic spectrum are absorbed by water molecules...

    ).

  • He consolidated and enhanced the work of Desains
    Paul-Quentin Desains
    Paul-Quentin Desains was a French physicist.He was born at Saint-Quentin, Aisne, France. He studied literature at the Collège des Bons-Enfants in his native town and then entered the Lycée Louis-le-Grand in Paris. Here he distinguished himself, taking the first prize in physics...

    , Forbes
    James David Forbes
    James David Forbes was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology. Forbes was a resident of Edinburgh for most of his life, educated at the University and a professor there from 1833 until he became principal of the United College of St...

    , Knoblauch and others 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.

  • When studying the absorption of radiant heat by ozone
    Ozone
    Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

    , he came up with a demonstration that helped confirm that ozone is an oxygen cluster.

  • Using his expertise about radiant heat absorption by gases, he invented a system for measuring the amount of carbon dioxide in a sample of exhaled human breath (1862, 1864). The basics of Tyndall's system is in daily use in hospitals today for monitoring patients under anesthesia. (See capnometry.)

  • Invented a better fireman's respirator
    Respirator
    A respirator is a device designed to protect the wearer from inhaling harmful dusts, fumes, vapors, or gases. Respirators come in a wide range of types and sizes used by the military, private industry, and the public...

    , a hood that filtered smoke and noxious gas from air (1871, 1874).

  • In the late 1860s and early 1870s he wrote an introductory book and several research reports about sound propagation in air, and was one of the chief participants in a large-scale British project that developed a better foghorn
    Foghorn
    A foghorn or fog signal or fog bell is a device that uses sound to warn vehicles of hazards or boats of the presence of other vehicles in foggy conditions. The term is most often used in relation to marine transport...

    . 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.)


An index of 19th century scientific research journals has John Tyndall as the author of more than 147 papers, with practically all of them dated between 1850 and 1884, which is an average of more than four papers a year over that 35-year period.

Tyndall was an experimenter and laboratory apparatus builder, not an abstract model builder. He did attempt to extend his studies on the heat-absorptive power of gases and vapors 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 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 radiant frequencies and he was entirely persuaded that the only difference between one frequency and another is the frequency. He'd also seen that the absorption behavior of molecules is quite different from that of the atoms composing the molecules — for example the gas nitric oxide (NO) absorbed more than a thousand times more infrared radiation than either nitrogen (N2) or oxygen (O2). He'd also seen in several kinds of experiments that no matter whether a gas is a weak absorber of broad-spectrum radiant heat, it will strongly absorb the radiant heat coming from a separate body of the same type of gas. That demonstrated a kinship between the molecular mechanisms of absorption
Absorption (electromagnetic radiation)
In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is...

 and emission. Such a kinship was also in evidence in experiments by Balfour Stewart
Balfour Stewart
Balfour Stewart was a Scottish physicist. His studies in the field of radiant heat led to him receiving the Rumford Medal of the Royal Society in 1868. In 1859 he was appointed director of Kew Observatory...

 and others, cited and extended by Tyndall, that showed with respect to broad-spectrum radiant heat that molecules that are weak absorbers are weak emitters and strong absorbers are strong emitters. (For example rock-salt is an exceptionally poor absorber of heat via radiation, and a good absorber of heat via conduction. When a plate of rock-salt is heated via conduction and let stand on an insulator, it takes an exceptionally long time to cool down; i.e., it's a poor emitter of infrared.) The kinship between absorption and emission was also consistent with some generic or abstract features of resonator
Resonator
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...

s. The photochemical effect convinced Tyndall that the resonator could not be the molecule as a whole unit; it had to be some substructure, because otherwise the photochemical effect would be impossible. But he was without testable ideas as to the form of this substructure, and did not partake in speculation in print. His promotion of the molecular mindset, and his efforts to experimentally expose what molecules are, has been discussed by one historian under the title "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
Total internal reflection
Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is...

 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
Jean-Daniel Colladon
Jean-Daniel Colladon was a Swiss physicist.- Life and work :Colladon studied law but then worked in the laboratories of Ampère and Fourier. He received an Académie des Sciences award with his friend Charles Sturm for their measurement of the speed of sound and the breaking up of water jets...

 published a report of it in Comptes Rendus
Comptes rendus
Comptes rendus de l'Académie des Sciences, or simply Comptes rendus, is a French scientific journal which has been published since 1666. It is the proceedings of the French Academy of Sciences...

 in 1842, and there's some suggestive evidence that Tyndall's knowledge of it came ultimately from Colladon and no evidence that Tyndall claimed to have originated it himself.

Alpine mountaineering and glaciology


Tyndall visited the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

 mountains in 1856 for scientific reasons and ended up becoming a pioneering mountain climber. He visited the Alps almost every summer from 1856 onward, was a member of the very first mountain-climbing team to reach the top of the Weisshorn
Weisshorn
The Weisshorn is a mountain in the Pennine Alps, in Switzerland. With its summit, it is one of the major peaks in the Alps and overtops the nearby Matterhorn by some 30 metres. It was first climbed in 1861 from Randa by John Tyndall, accompanied by the guides J.J...

 (1861), and lead of one of the early teams to reach the top of the Matterhorn
Matterhorn
The Matterhorn , Monte Cervino or Mont Cervin , is a mountain in the Pennine Alps on the border between Switzerland and Italy. Its summit is 4,478 metres high, making it one of the highest peaks in the Alps. The four steep faces, rising above the surrounding glaciers, face the four compass points...

 (1868). He is one the names associated with the "golden age of Alpinism
Golden age of alpinism
The golden age of alpinism was the period between Alfred Wills's ascent of the Wetterhorn in 1854 and Edward Whymper's ascent of the Matterhorn in 1865, during which many major peaks in the Alps saw their first ascents....

", i.e. the mid-Victorian years when the more difficult of the Alpine peaks were summited for the first time.

In the Alps, Tyndall studied glaciers, and especially glacier motion. His explanation of glacial flow brought him into dispute with others, particularly James David Forbes
James David Forbes
James David Forbes was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology. Forbes was a resident of Edinburgh for most of his life, educated at the University and a professor there from 1833 until he became principal of the United College of St...

. Much of the early scientific work had been done by Forbes, but Forbes at that time didn't know of the phenomenon of Regelation
Regelation
Regelation is the phenomenon of melting under pressure and freezing again when the pressure is reduced. Many textbooks and reference books as well as websites often claim that regelation can be demonstrated by looping a fine wire around a block of ice , with a heavy weight attached to it...

 which was discovered a little later by Michael Faraday. Regelation played a key role in Tyndall's explanation. Forbes didn't see regelation in the same way at all. Complicating their debate, a disagreement arose publicly over who deserved to get investigator credit for what. Articulate friends of Forbes, as well as Forbes himself, thought that 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
Louis Rendu
Louis Rendu was French Roman Catholic bishop of Annecy and a scientist. He was the author of Theorie des glaciers de la Savoie, an important book on the mechanisms of glacial motion....

; the proof of the quicker central flow belongs in part to Rendu, but almost wholly to Louis Agassiz
Louis Agassiz
Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...

 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." When 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
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 is named after John Tyndall, as is Mount Tyndall
Mount Tyndall
Mount Tyndall is a peak in the Mount Whitney region of the Sierra Nevada in the U.S. state of California. It rises to , and is the tenth highest peak in the state...

 in California and Mount Tyndall
Mount Tyndall (Tasmania)
Mount Tyndall is a mountain and high ground in the West Coast Range, Western Tasmania. The mountain was named after Irish scientist and mountaineer, John Tyndall.The surrounding high ground is often known as The Tyndalls or The Tyndall Range....

 in Tasmania.

Educator



Besides being 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
Athenaeum (magazine)
The Athenaeum was a literary magazine published in London from 1828 to 1921. It had a reputation for publishing the very best writers of the age....

and the Saturday Review
Saturday Review (London)
The Saturday Review of politics, literature, science, and art was a London weekly newspaper established by A. J. B. Beresford Hope in 1855....

in the UK, and Popular Science Monthly in the USA; and giving hundreds of public lectures to non-specialist audiences at the Royal Institution. When he went on a public lecture tour in the USA in 1872, large crowds paid fees to hear him lecture about the nature of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

. A typical statement of Tyndall's reputation at the time is this from a London publication in 1878: "Following the precedent set by 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 through 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 translated into German and French with his main tutorials staying in print in those languages for decades.

As an indicator of his teaching attitude, here are his concluding remarks to the reader at the end of a 200-page tutorial book (1872): "Here, my friend, our labours close. It has been a true pleasure to me to have you at my side so long. In the sweat of our brows we have often reached the heights where our work lay, but you have been steadfast and industrious throughout, using in all possible cases your own muscles instead of relying upon mine. Here and there I have stretched an arm and helped you to a ledge, but the work of climbing has been almost exclusively your own. It is thus that I should like to teach you all things; showing you the way to profitable exertion, but leaving the exertion to you.... Our task seems plain enough, but you and I know how often we have had to wrangle resolutely with the facts to bring out their meaning. The work, however, is now done, and you are master of a fragment of that sure and certain knowledge which is founded on the faithful study of nature.... Here then we part. And should we not meet again, the memory of these days will still unite us. Give me your hand. Good bye."

As another indicator, here is the opening paragraph of his 350-page tutorial entitled Sound (1867): "In the following pages I have tried to render the science of acoustics interesting to all intelligent persons, including those who do not possess any special scientific culture. The subject is treated experimentally throughout, and I have endeavoured so to place each experiment before the reader that he should realise it as an actual operation." In the preface to the 3rd edition of this book he reports that earlier editions were translated into Chinese at the expense of the Chinese government; and translated into German under the supervision of Hermann von Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...

 (a big name in the science of acoustics). His first published tutorial, which was about glaciers (1860), similarly states: "The work is written with a desire to interest intelligent persons who may not possess any special scientific culture."

His most widely praised tutorial, and perhaps also his biggest seller, was the 550-page "Heat: a Mode of Motion" (1863; updated editions until 1880). It was in print for at least 50 years, and is in print today. Its primary feature is as James Clerk Maxwell said, "the doctrines of the science [of heat] are forcibly impressed on the mind by well-chosen illustrative experiments."

His three longest tutorials, namely Heat (1863), Sound (1867), and Light (1873), represented state-of-the-art experimental physics at the time they were written. Much of their contents were recent major innovations in the understanding of their respective subjects, which Tyndall was the first writer to present to a wider audience. One caveat is called for about the meaning of "state of the art". The books were devoted to laboratory science and they avoided mathematics. In particular, they contain absolutely no infinitesimal calculus. Mathematical modeling using infinitesimal calculus, especially differential equations, was a component of the state-of-the-art understanding of heat, light and sound at the time.

Demarcation of science from religion


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
Balfour Stewart
Balfour Stewart was a Scottish physicist. His studies in the field of radiant heat led to him receiving the Rumford Medal of the Royal Society in 1868. In 1859 he was appointed director of Kew Observatory...

, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

, George Gabriel Stokes
George Gabriel Stokes
Sir George Gabriel Stokes, 1st Baronet FRS , was an Irish mathematician and physicist, who at Cambridge made important contributions to fluid dynamics , optics, and mathematical physics...

 and William Thomson
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...

 — all names investigating heat or light contemporaneously with Tyndall. These conservatives believed, and sought to strengthen the basis for believing, that religion and science were consistent and harmonious with each other. Tyndall, however, was a member of a club that vocally supported Darwin's theory of evolution and sought to strengthen the barrier, or separation, between religion and science. The most prominent member of this club was the anatomist Thomas Henry Huxley. Tyndall first met Huxley in 1851 and the two had a lifelong friendship. Chemist Edward Frankland
Edward Frankland
Sir Edward Frankland, KCB, FRS was a chemist, one of the foremost of his day. He was an expert in water quality and analysis, and originated the concept of combining power, or valence, in chemistry. He was also one of the originators of organometallic chemistry.-Biography:Edward Frankland was born...

 and mathematician Thomas Archer Hirst
Thomas Archer Hirst
Thomas Archer Hirst FRS was a 19th century mathematician, specialising in geometry. He was awarded the Royal Society's Royal Medal in 1883.-Life:...

, both of whom Tyndall had known since before going to university in Germany, were members too. Others included the social philosopher Herbert Spencer
Herbert Spencer
Herbert Spencer was an English philosopher, biologist, sociologist, and prominent classical liberal political theorist of the Victorian era....

. See X-Club.

Though not nearly so prominent as Huxley in controversy over philosophical problems, Tyndall played his part in communicating to the educated public what he thought were the virtues of having a clear separation between science (knowledge & rationality) and religion (faith & spirituality). As the elected president of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...

 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 Darwin's name favorably more than 20 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 scrutiny increased the friends of the evolutionists' philosophical position, and brought it closer to mainstream ascendancy.

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, Huxley and 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
Irish Home Rule Movement
The Irish Home Rule Movement articulated a longstanding Irish desire for the repeal of the Act of Union of 1800 by a demand for self-government within the United Kingdom of Great Britain and Ireland. The movement drew upon a legacy of patriotic thought that dated back at least to the late 17th...

. He had ardent views about it, which were published in newspapers and pamphlets. For example in an opinion piece in The Times
The Times
The Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...

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.

In several essays included in his book Fragments of Science for Unscientific People, Tyndall attempted to dissuade people from believing in the potential 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.

Private life



Tyndall did not marry until age 55. His bride, Louisa Hamilton, was the 30-year-old daughter of a member of parliament (Lord Claud Hamilton, M.P.). The following year, 1877, they built a summer chalet
Chalet
A chalet , also called Swiss chalet, is a type of building or house, native to the Alpine region, made of wood, with a heavy, gently sloping roof with wide, well-supported eaves set at right angles to the front of the house.-Definition and origin:...

 in the Swiss Alps. Before getting married Tyndall had been living for many years in an upstairs apartment at the Royal Institution and continued living there after marriage until 1885 when a move was made to a house near Haslemere
Haslemere
Haslemere is a town in Surrey, England, close to the border with both Hampshire and West Sussex. The major road between London and Portsmouth, the A3, lies to the west, and a branch of the River Wey to the south. Haslemere is approximately south-west of Guildford.Haslemere is surrounded by hills,...

 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 there is no evidence that he owned commercial patents). For many years he got non-trivial payments for being a part-time scientific advisor to a couple of quasi-governmental agencies and partly donated the payments to charity. His successful lecture tour of the United States in 1872 netted 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. When he died, his wealth was £22122. For comparison's sake, the income of a police constable in London was about £80 per year at the time.

In his last years Tyndall often took chloral hydrate
Chloral hydrate
Chloral hydrate is a sedative and hypnotic drug as well as a chemical reagent and precursor. The name chloral hydrate indicates that it is formed from chloral by the addition of one molecule of water. Its chemical formula is C2H3Cl3O2....

 to treat his insomnia
Insomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

. When bedridden and ailing, he died from an accidental overdose of this drug at age 73, and was buried at Haslemere
Haslemere
Haslemere is a town in Surrey, England, close to the border with both Hampshire and West Sussex. The major road between London and Portsmouth, the A3, lies to the west, and a branch of the River Wey to the south. Haslemere is approximately south-west of Guildford.Haslemere is surrounded by hills,...

. 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, whom Louisa Tyndall had authorized shortly before her death.

John Tyndall's books

  • The Glaciers of the Alps (470 pages) (1860)
  • Heat as a Mode of Motion (550 pages) (1863; revised later editions)
  • On Radiation: One Lecture (40 pages) (1865)
  • Sound: A Course of Eight Lectures (350 pages) (1867; revised later editions)
  • Faraday as a Discoverer (180 pages) (1868)
  • Natural Philosophy in Easy Lessons (180 pages) (1869) (a book intended for use in secondary schools)
  • Three Scientific Addresses by Prof. John Tyndall (75 pages) (1870)
  • Notes of a Course of Nine Lectures on Light (80 pages) (1870)
  • Notes of a Course of Seven Lectures on Electrical Phenomena and Theories (50 pages) (1870)
  • Researches on Diamagnetism and Magne-crystallic Action (380 pages) (1870) (a compilation of 1850s research reports)
  • Hours of Exercise in the Alps (450 pages) (1871)
  • Fragments of Science: A Series of Detached Essays, Lectures, and Reviews (over 500 pages) (1871; expanded later editions)
  • The Forms of Water in Clouds and Rivers, Ice and Glaciers (200 pages) (1872)
  • Contributions to Molecular Physics in the Domain of Radiant Heat (450 pages) (1872) (a compilation of 1860s research reports)
  • Six Lectures on Light (290 pages) (1873)
  • Lessons in Electricity at the Royal Institution (100 pages) (1876)
  • Essays on the Floating-matter of the Air in relation to Putrefaction and Infection (360 pages) (1881)
  • New Fragments (500 pages) (1892)

All of the above books can be freely downloaded at Archive.org.

Nearly all of them are in print and can be bought new.

Biographies of John Tyndall

430 pages. This is the "official" biography.
  • William T. Jeans wrote a 100-page biography of Professor Tyndall in 1887 (the year Tyndall retired from the Royal Institution). Downloadable
  • Louisa Charlotte Tyndall, his wife, wrote an 8-page biography of John Tyndall that appeared in 1903 as the preface to one of his books. Downloadable
  • Edward Frankland
    Edward Frankland
    Sir Edward Frankland, KCB, FRS was a chemist, one of the foremost of his day. He was an expert in water quality and analysis, and originated the concept of combining power, or valence, in chemistry. He was also one of the originators of organometallic chemistry.-Biography:Edward Frankland was born...

    , a longtime friend, wrote a 16-page biography of John Tyndall as an obituary in 1894 in a scientific journal. Downloadable gives an account of Tyndall's vocational development prior to 1853. 220 pages.
  • Arthur Whitmore Smith, a professor of physics, wrote a 10-page biography of John Tyndall in 1920 in a scientific monthly. Downloadable
  • John Walter Gregory
    John Walter Gregory
    John Walter Gregory, FRS, was a British geologist and explorer, known principally for his work on glacial geology and on the geography and geology of Australia and East Africa.-Early life:...

    , a naturalist, wrote a nine-page obituary of John Tyndall in 1894 in a natural science journal. Downloadable.
  • An early, seven-page profile of John Tyndall appeared in 1864 in Portraits of Men of Eminence in Literature, Science and Art (volume II) .
  • A brief profile of Tyndall, based on information supplied by Tyndall himself, appeared in 1874 in .
  • Claud Schuster
    Claud Schuster, 1st Baron Schuster
    Claud Schuster, 1st Baron Schuster, GCB, CVO, KC was a British barrister and civil servant noted for his long tenure as Permanent Secretary to the Lord Chancellor's Office. Born to a middle-class Mancunian family, Schuster was educated at St. George's School, Ascot and Winchester College before...

    , John Tyndall as a Mountaineer, 56-page essay included in Schuster's book Postscript to Adventure, year 1950 (New Alpine Library: Eyre & Spottiswoode
    Eyre & Spottiswoode
    Eyre & Spottiswoode, Ltd. was the London based printing firm that was the King's Printer, and subsequently, after April 1929, a publisher of the same name...

    , London).

See also

  • Ice sheet dynamics
    Ice sheet dynamics
    Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and strength of their bases...

  • Spontaneous generation
    Spontaneous generation
    Spontaneous generation or Equivocal generation is an obsolete principle regarding the origin of life from inanimate matter, which held that this process was a commonplace and everyday occurrence, as distinguished from univocal generation, or reproduction from parent...

  • John Tyndall's system for measuring radiant heat absorption in gases
  • Greenhouse gas
    Greenhouse gas
    A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...


External links