Giorgi, Giovanni

(b. Lucca, Italy. 27 November 1811; d. Castiglioncello, Italy. 19 August 1950)

electrical theory, electrical engineering, mathematics.

Giorgi’s father was an eminent jurist, who served as president of the Council of State and senator of the kingdom. From him Giorgi inherited a respect for scholarship and an austere way of life. Giorgi’s dedication to the doctrines of physics and their applications began early and lasted throughout his life; his more than 350 publications include works on engineering, pure physics, mathematical physics, electricity, magnetism, natural sciences, chemistry, and philosophy.

Giorgi took the degree in civil engineering from the Institute of Technology in Rome when he was twenty-two; his most important technological achievements include projects in steam-generated electrical traction, innovations in urban trolley systems, and pioneering concepts in hydroelectric installations (integral utilization of rivers) and distribution networks (as, for example, the secondary three-phase network with the fourth wire, used by him for the first time in Rome’s municipal installation). The work in large part coincided with his tenure as director of the Technology Office of the city of Rome from 1906 to 1923.

Giorgi’s teaching activities further reflect the scope of his interests. From 1913 to 1927 he taught courses in the Physics and Mathematics Faculty of the University of Rome, at the School of Aeronautics, and in the School of Engineering; he was later titular professor of mathematical physics and, by annual contract, head of the department of rational mechanics at the universities of Cagliari and Palermo. From 1934 he was professor of electrical communications at the University of Rome and in 1939 he became associate professor at the Royal Institute of Higher Mathematics. In addition to teaching and practical engineering, he did original scientific work (particularly in mathematics) and wrote popular treatments of scientific and technological subjects.

Giorgi’s chief fame, however, arises from his concept of a new absolute system of measurement to be simultaneously applicable to all electrical, magnetic, and mechanical units. In a letter to the English periodical Electrician, dated 28 March 1895 and published in April 1896, Giorgi took issue with the French physicist Alfred Cornu about the rationality of retaining the c.g.s. system of Wilhelm Weber and the English physicists, standardized in 1898. Giorgi held that the system, whose basic energy unit was the erg—one gram cm./sec.², or one centimeterdyne—was ill-adapted to current physics, given the connection between electrical and magnetic phenomena long since revealed by the researches of Oersted and Ampère.

Giorgi then devoted considerable time to the systematization of electrical units, and on 13 October 1901 presented to a meeting of the Italian Electrical Engineering Association a report entitled “Unità razionali di elettromagnetismo”—the cornerstone of his subsequent work. In this paper he proposed a consistent measurement system based on the meter, the kilogram, and the mean solar second (and hence called the M. K. S. system, as well as the Giorgi International System). The Giorgi system, of which the basic energy unit is the joule (one kg. meter²/sec.², or one meternewton), is adaptable to electrical, magnetic, netic, and mechanical units; is entirely composed of the standard units of mechanics; and requires no conversion factors since it is applicable to both electrostatic and electromagnetic systems. It therefore offers fewer irrationalities and greater convenience than the c.g.s. system because of its establishment of a single basic unit of appropriate size for each application.

Giorgi’s proposals were supported by Silvanus Thompson in England, Fritz Emde in Germany, and the U.S. Bureau of Standards, among others, but it was not until June 1935 that the plenary session of the International Electrical Engineering Commission, meeting in Scheveningen, Netherlands, and in Brussels, unanimously recommended the adoption of the new system of units to supersede the c.g.s. system. In October 1960 the General Conference of Weights and Measures confirmed the International System, based on the meter, the kilogram, and the second, as well as the ampere, kelvin, and candle. It is interesting to note that Giorgi himself had proposed the ohm or some other such unit as a fourth standard.

A half century thus elapsed between Giorgi’s letter to Electrician and the final adoption of a system based upon his principles. The Giorgi system is the clear manifestation of his versatility and of his abilities as a synthesizer.

BIBLIOGRAPHY

I. Original Works. Giorgi reprinted several of his works that are most important to reforms in the study of electrical engineering and the system of units—together with biographical data and a bibliography to December 1948 that lists more than 300 publications—in Verso l’elettrotecn ica moderna (Milan, 1949).

His textbooks include Lezioni di construzioni elettromeccaniche (Rome. 19Q5); Lezioni di meccanica generate (superiore) (Rome, 1914); Lezioni di Jisica matematica (eletiricità e magnetismo) (Cagliari, 1926); Lezioni di Jisica matematica (Rome, 1927); Compendio delle lezioni di meccanica razionale (Rome, 1928); Lezioni di meccanica razionale, 2. vols. (Rome, 1931–1934); Lezioni del corso di conununicazioni eletiriche (Rome, 1934–1939); Meccanica razionale (Rome, 1946); Compendio di storia delle matematiche (Turin, 1948); Aritmetica per scuole medic (Rome. 1948); and Verso l’elettrotecnica moderna (Milan, 1949).

His scientific popularizations include Le ferrovie a trazione eletirica (Bologna, 1905); Che cos’él’elettricito?, no. 8 in Collezione Omnia (Rome, 1928); Metrologia elettrotecnica antica e nuova (Milan, 1937), a repr. of three arts. published in Energia eletlrica, 14 , nos. 3–5 (Mar,-May, 1937); L ’etere e la luce (dall’etere cosmico alle moderne teorie delta luce), no. 32 in Collezione Omnia (Rome, 1939); and La frantumazione dell’atomo (Rome, 1946).

In addition, Giorgi wrote 37 papers on the new system of measurement, 32 on machinery and electrical installations, 14 on electrical traction, 45 on general electrical engineering, 93 on theories in mathematics and mathematical physics, 19 on the history of science, and 27 articles for the Enciclopedia italiana Treccani.

II. Secondary Literature. A very good summary of Giorgi’s life and work was given by Basilio Focaccia at the commemoration ceremony in Rome on 26 April 1951 and was published in Elettrotecnica38 (1951).

Mario Loria