John Hopkinson

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For the priest (his nephew), see John Hopkinson (priest).

John Hopkinson
Val d'Herens, Switzerland
NationalityBritish
Known forHopkinson effect
Hopkinson's law
Hopkinson's test
Three-phase electric power
AwardsRoyal Medal (1890)
Scientific career
Fieldsphysics, electrical engineering

John Hopkinson, FRS, (27 July 1849 – 27 August 1898) was a British

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 and electrostatics, and in 1890 was appointed professor of electrical engineering at King's College London, where he was also director of the Siemens Laboratory.[1]

Hopkinson's law, the magnetic counterpart to Ohm's law
, is named after him.

Life and career

John Hopkinson was born in

Cambridge Apostle
.

After working first in his father's engineering works, Hopkinson took a position in 1872 as an engineering manager in the

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 dynamos. 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.[3][4] He also studied magnetic permeability at high temperature, and discovered what was later called the Hopkinson peak effect.[5]

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.[6] 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.[7] 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).[8]

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

Memorial plaque at Cambridge

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, in the Pennine Alps, Switzerland.[9]

As a memorial to John Hopkinson and his son, the 1899 extension to the Engineering Laboratory in the New Museums Site of the University of Cambridge was named after him. A plaque commemorating this is fixed to the wall in Free School Lane.[10] The Hopkinson and Imperial Chemical Industries Professorship of Applied Thermodynamics is named in his honour.[11]

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 Electro-technical Laboratory (1912) in Coupland Street was named after him.[12]

His sons

Ascension Parish Burial Ground, Cambridge; the rest of the family are interred in Switzerland
.

See also

References

  1. Oxford Dictionary of National Biography
    : Hopkinson, John by T. H. Beare
  2. ^ "Hopkinson, John (HPKN867J)". A Cambridge Alumni Database. University of Cambridge.
  3. ^ Original papers on dynamo machinery and allied subjects (London, Whittaker, 1893)
  4. doi:10.1049/jste-3.1884.0048
    .
  5. JSTOR 90545
    .
  6. ^ Great Britain Patent 2989 of 1881.
  7. ^ US 385055 
  8. ^ Hopkinson v. Hunter (74 O.G., 653). United States Patent Office (1897). Decisions of the commissioner of patents and of the United States courts in patent and trade-mark and copyright cases. 1896. Washington, DC: Government Printing Office. pp. 1–5.
  9. ^ "The Unfortunate Hopkinson Family". Mr Boyd's Glacier Adventures. Retrieved 7 April 2023.
  10. ^ John Hopkinson biography
  11. ^ Cambridge University - 125 Years of Engineering Excellence
  12. ^ The Book of Manchester and Salford. Manchester: George Falkner & Sons, 1929; p. 73

Further reading

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

External links

Wikisource has the text of the 1911 Encyclopædia Britannica article "Hopkinson, John".
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