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John Hopkinson, FRS, (27 July 1849 – 27 August 1898) was a British
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...
,
electrical engineer Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the ...
, Fellow of the Royal Society and President of the IEE (now the IET) twice in 1890 and 1896. He invented the three-wire ( three-phase) system for the distribution of electrical power, for which he was granted a patent in 1882. He also worked in many areas of
electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of ...
and
electrostatics Electrostatics is a branch of physics that studies electric charges at rest ( static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amb ...
, and in 1890 was appointed professor of electrical engineering at King's College London, where he was also director of the Siemens Laboratory. Hopkinson's law, the magnetic counterpart to
Ohm's law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equa ...
, is named after him.


Life and career

John Hopkinson was born in Manchester, the eldest of 5 children. His father, also called John, was a mechanical engineer. He was educated at Queenwood School in Hampshire and Owens College in Manchester. He won a scholarship to
Trinity College, Cambridge Trinity College is a constituent college of the University of Cambridge. Founded in 1546 by King Henry VIII, Trinity is one of the largest Cambridge colleges, with the largest financial endowment of any college at either Cambridge or Oxford. ...
in 1867 and graduated in 1871 as Senior Wrangler, having placed first in the demanding
Cambridge Mathematical Tripos The Mathematical Tripos is the mathematics course that is taught in the Faculty of Mathematics at the University of Cambridge. It is the oldest Tripos examined at the University. Origin In its classical nineteenth-century form, the tripos was a ...
examination. During this time he also studied for and passed the examination for a BSc from the University of London. Hopkinson could have followed a purely academic career but instead chose engineering as his vocation. He was a
Cambridge Apostle The Cambridge Apostles (also known as ''Conversazione Society'') is an intellectual society at the University of Cambridge founded in 1820 by George Tomlinson, a Cambridge student who became the first Bishop of Gibraltar.W. C. Lubenow, ''The C ...
. After working first in his father's engineering works, Hopkinson took a position in 1872 as an engineering manager in the
lighthouse A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark ...
engineering department of Chance Brothers and Company in Smethwick. In 1877 Hopkinson was elected a Fellow of the Royal Society in recognition of his application of
Maxwell Maxwell may refer to: People * Maxwell (surname), including a list of people and fictional characters with the name ** James Clerk Maxwell, mathematician and physicist * Justice Maxwell (disambiguation) * Maxwell baronets, in the Baronetage of ...
's theory of
electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of ...
to problems of electrostatic capacity and residual charge. In 1878 he moved to London to work as a consulting engineer, focusing particularly on developing his ideas about how to improve the design and efficiency of
dynamo "Dynamo Electric Machine" (end view, partly section, ) A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundat ...
s. Hopkinson's most important contribution was his three-wire distribution system, patented in 1882. In 1883 Hopkinson showed mathematically that it was possible to connect two alternating current dynamos in parallel-—a problem that had long bedevilled electrical engineers. He also studied magnetic permeability at high temperature, and discovered what was later called the Hopkinson peak effect. The series-parallel method of electric motor control, for which Hopkinson was granted a British patent in 1881, would prove to be an important advance in the development of electric railways. He applied for a US patent in 1892, triggering an interference proceeding against American inventor Rudolph M Hunter, who had been granted a US patent for the method in 1888. The US Patent Office affirmed Hopkinson's claim to priority of invention, but his British patent expired before the case was resolved, rendering him ineligible for a US patent (his US patent, had one been issued, would have expired concurrently with his British patent). Hopkinson twice held the office of President of the Institution of Electrical Engineers. During his second term, Hopkinson proposed that the Institution should make available the technical knowledge of electrical engineers for the defence of the country. In 1897 the Volunteer Corps of Electrical Engineers was formed and Hopkinson became major in command of the corps.


Personal life and legacy

On 27 August 1898, Hopkinson and three of his six children, John Gustave, Alice and Lina Evelyn, were killed in a mountaineering accident on the Petite Dent de Veisivi,
Val d'Hérens Val d'Hérens is an alpine valley in the Valais canton of Switzerland. It was formed by the Hérens glacier, which retreated at the end of the last ice age. It is now the valley of the ''Borgne'' river, a tributary of the Rhone (confluence abo ...
, in the
Pennine Alps The Pennine Alps (german: Walliser Alpen, french: Alpes valaisannes, it, Alpi Pennine, la, Alpes Poeninae), also known as the Valais Alps, are a mountain range in the western part of the Alps. They are located in Switzerland (Valais) and Ital ...
, Switzerland. As a memorial to John Hopkinson and his son, the 1899 extension to the Engineering Laboratory in the
New Museums Site The New Museums Site is a major site of the University of Cambridge, located on Pembroke Street and Free School Lane, sandwiched between Corpus Christi College, Pembroke College and Lion Yard. Its postcode is CB2 3QH. The smaller and older of ...
of the University of Cambridge was named after him. A plaque commemorating this is fixed to the wall in
Free School Lane Free School Lane is a historic street in central Cambridge, England which includes important buildings of University of Cambridge. It is the location of the Whipple Museum of the History of Science, the Department of History and Philosophy of ...
. The Hopkinson and Imperial Chemical Industries Professorship of Applied Thermodynamics is named in his honour. There is a memorial sundial to Alice Hopkinson in the gardens of Newnham College, Cambridge from which she had recently graduated; the Lina Evelyn Hopkinson Scholarship is awarded to pupils at Wimbledon High School for English Literature. At the
Victoria University of Manchester The Victoria University of Manchester, usually referred to as simply the University of Manchester, was a university in Manchester, England. It was founded in 1851 as Owens College. In 1880, the college joined the federal Victoria University. Afte ...
the Electro-technical Laboratory (1912) in Coupland Street was named after him.''The Book of Manchester and Salford''. Manchester: George Falkner & Sons, 1929; p. 73 His sons Bertram and Cecil, wife Evelyn and daughter Ellen (married James Alfred Ewing in 1912) are buried in the
Ascension Parish Burial Ground, Cambridge The Ascension Parish Burial Ground, formerly known as the burial ground for the parish of St Giles and St Peter's, is a cemetery off Huntingdon Road in Cambridge, England. Many notable University of Cambridge academics are buried there, inclu ...
; the rest of the family are interred in Switzerland.


See also

* Electric motor *
Three-phase electric power Three-phase electric power (abbreviated 3φ) is a common type of alternating current used in electricity generation, transmission, and distribution. It is a type of polyphase system employing three wires (or four including an optional neutral ...
* Polyphase system * Rigid collectors * Bertram Hopkinson, his son *
Alfred Hopkinson Sir Alfred Hopkinson (28 June 1851 – 11 November 1939) was an English lawyer, academic and politician who served as a Member of Parliament (MP) for two three-year periods, separated by nearly thirty years. He was the son of John Hopkinson, a m ...
and Edward Hopkinson, his younger brothers * Austin Hopkinson, his nephew


References


Further reading

*Hopkinson, Mary & Ewing, Irene, ''Lady'' (eds.) (1948) ''John and Alice Hopkinson 1824-1910''. London: Farmer & Sons, printers


External links

*
John Hopkinson
{{DEFAULTSORT:Hopkinson, John 1849 births 1898 deaths Scientists from Manchester Alumni of Trinity College, Cambridge Alumni of the University of London English scientists Fellows of the Royal Society English electrical engineers English physicists Academics of King's College London Mountaineering deaths Sport deaths in Switzerland Royal Medal winners Senior Wranglers John