John Sealy Townsend
Encyclopedia
John Sealy Edward Townsend, FRS (7 June 1868 – 16 February 1957) was a mathematical physicist
who conducted various studies concerning the electrical conduction of gas
es (concerning the kinetics
of electron
s and ion
s) and directly measured the electrical charge. He was a Wykeham Professor
of physics at Oxford University.
, County Galway
, Ireland
, son of Edward Townsend, a Professor of Civil Engineering at Queen's College, Galway. In 1885, he entered Trinity College Dublin and came top of the class in maths with a BA in 1890. He became a Clerk Maxwell Scholar and entered Trinity College, Cambridge
, where he became a research student at the same time as Ernest Rutherford
. At the Cavendish laboratory
, he studied under J. J. Thomson
. He developed the "Townsend's collision theory". Townsend supplied important work to the electrical conductivity of gases ("Townsend discharge
" circa 1897). This work determined the elementary electrical charge
with the droplet method. This method was improved later by Robert Andrews Millikan.
In 1900, he became a Wykeham Professor
of Physics at Oxford
. In 1901, he discovered the ionization of molecules by ion impact and the dependence of the mean free path on electron
s (in gases) of the energy (and his independent studies concerning the collisions between atoms and low-energy electrons in the 1920s would later be called the Ramsauer-Townsend effect
). On June 11, 1903, he was elected to Fellow of the Royal Society(FRS). He was awarded the Hughes Medal
in 1914. During World War I
, he researched, at Woolwich
, wireless
methods for the Royal Naval Air Service
.
Townsend was a laboratory demonstrator when Brebis Bleaney
was an undergraduate. Bleaney recounts an occasion when Townsend gathered together all the demonstrators and proceeded to refute both quantum mechanics and relativity.
Between the two world wars, Townsend led an effective small group of researchers, often Rhodes scholars, of whom some became distinguished physicists. However, by the 1930s he had become less effective. He was seen as a boring lecturer, a dogmatic supervisor, and out of touch with the wider world of physics. As the 1930s went on, no German refugees sought refuge in his laboratory, while Lindemann
, Dr Lee's professor of Physics, gained eight refugee physicists, some of whom gave his department an international reputation in the world of low temperature physics. In the late 1930s, the University decided to build a new Clarendon Building and looked closely at the relations between Oxford's two physics laboratories. There was a suggestion to convert the Wykeham chair into one for theoretical physics. In 1941, Townsend's career came to an unhappy end. He had refused to support the war effort by teaching service-men, and the university appointed a visitatorial board. This found Townsend guilty of misconduct and advised him that he would be dismissed unless he agreed to resign. Townsend, knighted in January 1941, resigned in September, subject to confidentiality.
He spent his retirement in Oxford, where he died in 1957 in the Acland Nursing Home.
Townsend married May Georgina, also from County Galway, and they had two sons. His wife took an interest in politics, became a city councillor, and was twice Mayor of Oxford.
Mathematical physics
Mathematical physics refers to development of mathematical methods for application to problems in physics. The Journal of Mathematical Physics defines this area as: "the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and...
who conducted various studies concerning the electrical conduction of gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
es (concerning the kinetics
Kinetics (physics)
In physics and engineering, kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques...
of electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s and ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s) and directly measured the electrical charge. He was a Wykeham Professor
Wykeham Professor
The University of Oxford has three statutory professorships named after William of Wykeham.-Logic:The Wykeham Professorship in Logic was established in 1859, although it was not known as the Wykeham chair until later...
of physics at Oxford University.
Career
He was born in GalwayGalway
Galway or City of Galway is a city in County Galway, Republic of Ireland. It is the sixth largest and the fastest-growing city in Ireland. It is also the third largest city within the Republic and the only city in the Province of Connacht. Located on the west coast of Ireland, it sits on the...
, County Galway
County Galway
County Galway is a county in Ireland. It is located in the West Region and is also part of the province of Connacht. It is named after the city of Galway. Galway County Council is the local authority for the county. There are several strongly Irish-speaking areas in the west of 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...
, son of Edward Townsend, a Professor of Civil Engineering at Queen's College, Galway. In 1885, he entered Trinity College Dublin and came top of the class in maths with a BA in 1890. He became a Clerk Maxwell Scholar and entered Trinity College, Cambridge
Trinity College, Cambridge
Trinity College is a constituent college of the University of Cambridge. Trinity has more members than any other college in Cambridge or Oxford, with around 700 undergraduates, 430 graduates, and over 170 Fellows...
, where he became a research student at the same time as Ernest Rutherford
Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson OM, FRS was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics...
. At the Cavendish laboratory
Cavendish Laboratory
The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the university's School of Physical Sciences. It was opened in 1874 as a teaching laboratory....
, he studied under J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...
. He developed the "Townsend's collision theory". Townsend supplied important work to the electrical conductivity of gases ("Townsend discharge
Townsend discharge
The Townsend discharge is a gas ionization process where an initially very small amount of free electrons, accelerated by a sufficiently strong electric field, give rise to electrical conduction through a gas by avalanche multiplication: when the number of free charges drops or the electric field...
" circa 1897). This work determined the elementary electrical charge
Elementary charge
The elementary charge, usually denoted as e, is the electric charge carried by a single proton, or equivalently, the absolute value of the electric charge carried by a single electron. This elementary charge is a fundamental physical constant. To avoid confusion over its sign, e is sometimes called...
with the droplet method. This method was improved later by Robert Andrews Millikan.
In 1900, he became a Wykeham Professor
Wykeham Professor
The University of Oxford has three statutory professorships named after William of Wykeham.-Logic:The Wykeham Professorship in Logic was established in 1859, although it was not known as the Wykeham chair until later...
of Physics at Oxford
University of Oxford
The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...
. In 1901, he discovered the ionization of molecules by ion impact and the dependence of the mean free path on electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s (in gases) of the energy (and his independent studies concerning the collisions between atoms and low-energy electrons in the 1920s would later be called the Ramsauer-Townsend effect
Ramsauer-Townsend effect
The Ramsauer–Townsend effect, also sometimes called the Ramsauer effect or the Townsend effect, is a physical phenomenon involving the scattering of low-energy electrons by atoms of a noble gas...
). On June 11, 1903, he was elected to Fellow of the Royal Society(FRS). He was awarded the Hughes Medal
Hughes Medal
The Hughes Medal is awarded by the Royal Society of London "in recognition of an original discovery in the physical sciences, particularly electricity and magnetism or their applications". Named after David E. Hughes, the medal is awarded with a gift of £1000. The medal was first awarded in 1902 to...
in 1914. During World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, he researched, at Woolwich
Woolwich
Woolwich is a district in south London, England, located in the London Borough of Greenwich. The area is identified in the London Plan as one of 35 major centres in Greater London.Woolwich formed part of Kent until 1889 when the County of London was created...
, wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...
methods for the Royal Naval Air Service
Royal Naval Air Service
The Royal Naval Air Service or RNAS was the air arm of the Royal Navy until near the end of the First World War, when it merged with the British Army's Royal Flying Corps to form a new service , the Royal Air Force...
.
Townsend was a laboratory demonstrator when Brebis Bleaney
Brebis Bleaney
Brebis Bleaney CBE FRS was a British physicist. His main area of research was the use of microwave techniques to study the magnetic properties of solids. He was head of the Clarendon Laboratory at the University of Oxford from 1957 to 1977...
was an undergraduate. Bleaney recounts an occasion when Townsend gathered together all the demonstrators and proceeded to refute both quantum mechanics and relativity.
Between the two world wars, Townsend led an effective small group of researchers, often Rhodes scholars, of whom some became distinguished physicists. However, by the 1930s he had become less effective. He was seen as a boring lecturer, a dogmatic supervisor, and out of touch with the wider world of physics. As the 1930s went on, no German refugees sought refuge in his laboratory, while Lindemann
Frederick Lindemann, 1st Viscount Cherwell
Frederick Alexander Lindemann, 1st Viscount Cherwell FRS PC CH was an English physicist who was an influential scientific adviser to the British government, particularly Winston Churchill...
, Dr Lee's professor of Physics, gained eight refugee physicists, some of whom gave his department an international reputation in the world of low temperature physics. In the late 1930s, the University decided to build a new Clarendon Building and looked closely at the relations between Oxford's two physics laboratories. There was a suggestion to convert the Wykeham chair into one for theoretical physics. In 1941, Townsend's career came to an unhappy end. He had refused to support the war effort by teaching service-men, and the university appointed a visitatorial board. This found Townsend guilty of misconduct and advised him that he would be dismissed unless he agreed to resign. Townsend, knighted in January 1941, resigned in September, subject to confidentiality.
He spent his retirement in Oxford, where he died in 1957 in the Acland Nursing Home.
Townsend married May Georgina, also from County Galway, and they had two sons. His wife took an interest in politics, became a city councillor, and was twice Mayor of Oxford.
Works
- The Theory of Ionisation of Gases by Collision (1910)
- Motion of Electrons in Gases (1925)
- Electricity and Radio Transmission (1943)
- Electromagnetic Waves (1951)
External links
- "Papers and correspondence of Sir John Sealy Edward Townsend, 1868-1957". Bodleian Library, Oxford. (ed. compiled between 1914-1957.)
- Entry in The Townsend (Townshend) Family Records