John Hopkinson

John Hopkinson, FRS, (27 July 1849 – 27 August 1898) was a British physicist, electrical engineer, Fellow of the Royal Society and President of the IEE 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 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 Manchester, the eldest of 13 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 in 1867. He graduated in 1871 as Senior Wrangler, having placed first in the demanding Cambridge Mathematical Tripos examination.^[2] 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.

After working first in his father's engineering works, Hopkinson took a position in 1872 as an engineering manager in the lighthouse 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's theory of electromagnetism 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 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 bedeviled electrical engineers.^[3]

Accidental death

Hopkinson and three of his children were killed in 1898 in a mountaineering accident on Mount Petite Dent de Veisivi, Val d'Herens, Switzerland.

As a memorial to John Hopkinson and his son, the 1899 extension to the Engineering Laboratory in the New Museums Site of University of Cambridge was named after him. A plaque commemorating this is fixed to the wall in Free School Lane.^[4] The Hopkinson and Imperial Chemical Industries Professorship of Applied Thermodynamics is named in his honour.^[5]

See also

• Electric motor
• Three-phase electric power
• Polyphase system
• Bertram Hopkinson, his son
• Edward Hopkinson, his younger brother
• Austin Hopkinson, his nephew

References

1. ^ Oxford Dictionary of National Biography: Hopkinson, John by T. H. Beare
2. ^ Hopkinson, John in Venn, J. & J. A., Alumni Cantabrigienses, Cambridge University Press, 10 vols, 1922–1958.
3. ^ Original papers on dynamo machinery and allied subjects (London, Whittaker, 1893)
4. ^ John Hopkinson biography
5. ^ Cambridge University - 125 Years of Engineering Excellence

External links

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

• Works by John Hopkinson at Internet Archive. Scanned, illustrated original editions.
• John Hopkinson
• John Hopkinson Biography