John Hopkinson, FRS, was born on July 27, 1849, and died on August 27, 1898. He was a British physicist and electrical engineer who became a member of the Royal Society. He served as president of the IEE (now called the IET) twice, in 1890 and 1896. In 1882, he was granted a patent for inventing the three-wire (three-phase) system, which is used to distribute electrical power. He also worked on topics related to electromagnetism and electrostatics. In 1890, he was made a professor of electrical engineering at King's College London, where he also directed the Siemens Laboratory.
A scientific principle called Hopkinson's law, which is the magnetic version of Ohm's law, is named after him.
Life and career
John Hopkinson was born in Manchester and was the oldest of five children. His father, also named John, was a mechanical engineer. He attended Queenwood School in Hampshire and Owens College in Manchester. In 1867, he earned a scholarship to Trinity College, Cambridge, where he graduated in 1871 as Senior Wrangler, meaning he placed first in the Cambridge Mathematical Tripos examination. During this time, he also completed a BSc from the University of London. Although he could have pursued an academic career, he chose engineering as his profession. He was a member of the Cambridge Apostles.
After working initially in his father’s engineering business, Hopkinson joined Chance Brothers and Company in Smethwick in 1872 as an engineering manager in their lighthouse department. In 1877, he was elected a Fellow of the Royal Society for applying Maxwell’s theory of electromagnetism to problems involving electrostatic capacity and residual charge. In 1878, he moved to London to work as a consulting engineer, focusing on improving the design and efficiency of dynamos. His most significant contribution was the invention of the three-wire distribution system, patented in 1882. In 1883, he proved mathematically that two alternating current dynamos could be connected in parallel, solving a long-standing challenge for electrical engineers. He also studied magnetic permeability at high temperatures and discovered what later became known as the Hopkinson peak effect.
In 1881, Hopkinson received a British patent for the series-parallel method of electric motor control, an innovation that later became important for the development of electric railways. He applied for a US patent in 1892, which led to a legal dispute with American inventor Rudolph M. Hunter, who had been granted a US patent for the same method in 1888. The US Patent Office ruled in Hopkinson’s favor, but his British patent had expired before the case was resolved, preventing him from receiving a US patent.
Hopkinson served twice as President of the Institution of Electrical Engineers. During his second term, he proposed that the Institution should share electrical engineering knowledge to support national defense. In 1897, the Volunteer Corps of Electrical Engineers was formed, and Hopkinson became a major in command of the corps.
Personal life and legacy
Hopkinson was a member of the Alpine Club from 1889 until his death. Before joining the club, he was an active mountaineer in the Alps for many years. He climbed with his brothers, Charles and Edward, and his son Bertram and daughter Alice joined him on some climbs. His climbing included first ascents and new routes that he completed without guides. A summary of his climbing achievements is recorded in Mumm's Alpine Register.
On August 27, 1898, Hopkinson and three of his six children—John Gustave, Alice, and Lina Evelyn—died in a mountaineering accident on the Petite Dent de Veisivi in Val d'Hérens, part of the Pennine Alps in Switzerland.
To honor John Hopkinson and his son, the 1899 addition to the Engineering Laboratory at the New Museums Site at the University of Cambridge was named after him. A plaque on the wall in Free School Lane commemorates this. The Hopkinson Professorship of Applied Thermodynamics (later known as the Hopkinson and Imperial Chemical Industries Professorship of Applied Thermodynamics) was established in his memory.
A sundial in the gardens of Newnham College, Cambridge, honors Alice Hopkinson, who had recently graduated from the college. The Lina Evelyn Hopkinson Scholarship is given to students at Wimbledon High School for outstanding achievement in English Literature.
At the Victoria University of Manchester (now part of UMIST, which later merged with the University of Manchester), the Electro-technical Laboratory (built in 1912) in Coupland Street, Manchester, was named after him.
Hopkinson’s wife, Evelyn (née Oldenburg), his sons Bertram and Cecil (christened Rudolf), and his daughter Ellen (who married James Alfred Ewing in 1912) are buried in the Ascension Parish Burial Ground in Cambridge. The rest of the family is buried at Cimetière de Territet, part of St John's English Church in Territet, a town south of Montreux, Switzerland. Cecil (1891–1917) shared a room with Lawrence Bragg at Trinity College, Cambridge, and they became close friends. Cecil suffered a serious head injury during the 1914–19 war and died months after returning to the UK. Bragg later married Cecil’s cousin, Alice Hopkinson.