Giovanni Giorgi

Giovanni Giorgi (November 27, 1871 – August 19, 1950) was an Italian physicist and electrical engineer who proposed the Giorgi system of measurement, the precursor to the International System of Units (SI).

Giovanni Giorgi
Giovanni Giorgi.jpg
Giovanni Giorgi
Born(1871-11-27)27 November 1871
Died19 August 1950(1950-08-19) (aged 78)
Engineering career
InstitutionsUniversity of Rome
ProjectsGiorgi system of measurement

Early LifeEdit

Giovanni Giorgi was born in Lucca on November 27, 1871.


Giorgi 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 1905 and 1924. He also taught at the University of Rome between 1913 and 1939. During World War II he moved to Ferentino. He was an Invited Speaker of the ICM in 1924 in Toronto,[1] in 1928 in Bologna, and in 1932 in Zurich.

Personal lifeEdit

He was engaged to Laura Pisati, his former master's student who became the first woman invited to deliver a lecture at the fourth International Congress of Mathematicians (ICM), but she died in 1908 shortly before both her talk and their intended wedding.[2]


Giorgi died on August 19, 1950, in Castiglioncello, Livorno at the age of 78.[3]

The Giorgi systemEdit

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 base 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 [it] (AEI) that the MKS system (which used the metre, kilogram and second as its base units) should be extended with a fourth unit to be chosen from the units of electromagnetism, solving also the presence of the irrational coefficients.[4][5][6][7]

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 base unit.[8] 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.[9]

The Giorgi system was thus the precursor of the International System of Units (SI) adopted in 1960, which was based on six base units: metre, kilogram, second, ampere, kelvin, and candela.[9] The mole was added as a seventh base unit in 1971.[10]


  • Compendio delle lezioni di meccanica razionale (in Italian). Roma: Sampaolesi. 1928.
  • Lezioni di fisica matematica (in Italian). Roma: Sampaolesi. 1928.


  1. ^ 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.
  2. ^ Mihaljević, Helena; Roy, Marie-Françoise (2019). "A Data Analysis of Women's Trails Among ICM Speakers". In Araujo, Carolina; Benkart, Georgia; Praeger, Cheryl E.; Tanbay, Betül (eds.). World Women in Mathematics 2018. Association for Women in Mathematics Series. Springer International Publishing. pp. 111–128. arXiv:1903.02543. doi:10.1007/978-3-030-21170-7_5. S2CID 70349983.
  3. ^ "Giovanni Giorgi". Physics Today. November 27, 2018. doi:10.1063/PT.6.6.20181127a. Retrieved May 21, 2021.
  4. ^ Giovanni Giorgi (1901), "Unità Razionali di Elettromagnetismo", Atti della Associazione Elettrotecnica Italiana (in Italian), Torino, OL 18571144M
  5. ^ Giovanni Giorgi (1902), Rational Units of Electromagnetism. Original manuscript with handwritten notes by Oliver Heaviside
  6. ^ Giovanni Giorgi (1934), "Memorandum on the M.K.S. System of Practical Units", Central Office of the International Electrotechnical Commission, London, 9: 1–6, doi:10.1109/LMAG.2018.2859658
  7. ^ 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 Propag. Mag., 57 (6): 152–165, Bibcode:2015IAPM...57..152F, doi:10.1109/MAP.2015.2486765, ISSN 1045-9243, S2CID 42813124
  8. ^ 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, PMID 16577693
  9. ^ a b Le Système international d’unités [The International System of Units] (PDF) (in French and English) (9th ed.), International Bureau of Weights and Measures, 2019, p. 205, ISBN 978-92-822-2272-0
  10. ^ National Institute of Standards and Technology, Brief history of the SI, retrieved 2015-01-15


  1. International Electrotechnical Commission. "IEC Historical Figures - Giovanni Giorgi". Retrieved 2014-02-21.
  2. Giovanni Giorgi (1905), "Proposals Concerning Electrical and Physical Units", Transactions of the International Electrical Congress, St. Louis, 1904, Albany, N.Y., J.B. Lyon Company: 136–141, OCLC 3395740