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27 November 1871|
19 August 1950 (aged 78)|
|Institutions||University of Rome|
|Projects||Giorgi system of measurement|
Giovanni Giorgi (27 November 1871 – 19 August 1950) was an Italian physicist and electrical engineer who proposed the Giorgi system of measurement, the precursor to the International System of Units (SI).
Giorgi was born in Lucca and studied engineering at the Institute of Technology of Rome, he worked at Fornaci Giorgi in Ferentino, then was the director of the Technology Office of Rome between 1906 and 1923. He also taught at the University of Rome between 1913 and 1939. During World War II he moved to Ferentino.
The Giorgi system
Toward the end of the 19th century, after James Clerk Maxwell's discoveries, it was clear that electric measurements could not be explained in terms of the three fundamental units of length, mass and time, and that some irrational coefficients appeared in the equations without any logical physical reason. In 1901, Giorgi proposed to the Associazione elettrotecnica italiana (AEI) that the MKS system (which used the metre, kilogram and second as its fundamental units) should be extended with a fourth unit to be chosen from the units of electromagnetism, solving also the presence of the irrational coefficients.
In 1935 this was adopted by the International Electrotechnical Commission (IEC) as the M.K.S. System of Giorgi without specifying which electromagnetic unit would be the fourth fundamental unit. In 1946 the International Committee for Weights and Measures (CIPM) approved a proposal to use the ampere as that unit in a four-dimensional system, the MKSA system.
The Giorgi system was thus the precursor of the International System of Units (SI) adopted in 1960, which was based on six fundamental units: metre, kilogram, second, ampere, kelvin, and candela. The mole was added as a seventh fundamental unit in 1971. 
- Giorgi, Giovanni. "On the functional dependence of physical variables". In: Proceedings of the International Congress of Mathematicians in Toronto, August 11–16. 1924. vol. 2. pp. 31–56.
- Giovanni Giorgi (1901), "Unità Razionali di Elettromagnetismo", Atti della Associazione Elettrotecnica Italiana (in Italian), Torino
- Giovanni Giorgi (1902), Rational Units of Electromagnetism Original manuscript with handwritten notes by Oliver Heaviside
- Giovanni Giorgi (1934), "Memorandum on the M.K.S. System of Practical Units", Central Office of the International Electrotechnical Commission, London, retrieved 2018-09-10
- F. Frezza; S. Maddio; G. Pelosi; S. Selleri (2015), "The Life and Work of Giovanni Giorgi: The Rationalization of the International System of Units", IEEE Antennas Propagat. Mag., 57 (6): 152–165, Bibcode:2015IAPM...57..152F, doi:10.1109/MAP.2015.2486765, ISSN 1045-9243
- Arthur E. Kennelly (1935), "Adoption of the Meter-Kilogram-Mass-Second (M.K.S.) Absolute System of Practical Units by the International Electrotechnical Commission (I.E.C.), Bruxelles, June, 1935", Proceedings of the National Academy of Sciences of the United States of America, 21 (10): 579–583, Bibcode:1935PNAS...21..579K, doi:10.1073/pnas.21.10.579, PMC 1076662
- International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), pp. 109, 110, ISBN 92-822-2213-6, archived (PDF) from the original on 2017-08-14
- National Institute of Standards and Technology, "Brief history of the SI", retrieved 2015-01-15
- International Electrotechnical Commission. "IEC Historical Figures - Giovanni Giorgi". Retrieved 2014-02-21.
- Giovanni Giorgi (1905), "Proposals Concerning Electrical and Physical Units", Transactions of the International Electrical Congress, St. Louis, 1904: 136–141, OCLC 3395740