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To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Giovanni Giorgi's contribution to the rationalized system of units, 1901-1902

Plaque citation summarizing the achievement and its significance:

In October 1901 in Rome Giovanni Giorgi, an Italian engineer who graduated and later became Professor at the University of Rome, proposed to rationalize the equations of electromagnetism and to add a fourth unit to the three mechanical units of measurements (meter, kilogram, second). That was the origin of the International System of units (SI) currently used and named also “Giorgi system”.

In what IEEE section(s) does it reside?

IEEE Italy Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Italy Section
Senior Officer Name: Senior officer name masked to public

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: IEEE Italy Section
Senior Officer Name: Senior officer name masked to public

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Italy Section
IEEE Section Chair name: Section chair name masked to public

Milestone proposer(s):

Proposer name: Proposer's name masked to public
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates of the intended milestone plaque site(s):

Via Eudossiana 18, 00184 Rome, Italy Latitude 41.889187 Longitude 12.498257200000012

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The site is the historic site of the Faculty of Engineering. Yes, there are already other historical markers.

Are the original buildings extant?


Details of the plaque mounting:

The mounting is predicted in the ground floor entrance hall

How is the site protected/secured, and in what ways is it accessible to the public?

The plaque will be freely accessible to the public. During the opening hours, staff in charge is always present. A night watchman is provided as well.

Who is the present owner of the site(s)?

"La Sapienza" University of Rome, Italy, Faculty of Civil and Industrial Engineering

What is the historical significance of the work (its technological, scientific, or social importance)?

As a consequence of the mechanical-centered vision of physics, dominant for nearly all of the 19th century—such that all the physical phenomena could be explained by the fundamental concepts of mechanics—the previously mentioned choices seemed to be the right ones as, in this way, all the electromagnetic units could be derived from the mechanical ones. However, it was just this absurd assumption that caused the great confusion in the field of the systems of units—this confusion led to the proposal of a new system by the Italian engineer Giovanni Giorgi at the beginning of the 20th century. Carl Friedrich Gauss (1777–1855) was the first to formulate the concept of the “absolute system,” a system in which the values of the units do not vary from place to place, as it happens, for example, for the kilogram-force. In his system, all of the units were derived from the three fundamental units of length, mass, and time (millimeter, milligram, and second). In particular, the units for the electrostatic quantities were defined through the first Coulomb law with ke=1. Usually, two other conditions are required from an absolute system: the number of the fundamental units should be small enough and the secondary units should be defined by formulas without spurious numerical coefficients. The work of Gauss was continued by Wilhelm Eduard Weber (1804–1891) on the basis of the fundamental units, millimeter–milligram–second. Weber showed how absolute measurements of resistance could be made by reducing all electrical magnitudes to measurements of mass, length, and time. The Gauss–Weber system was soon followed by many other absolute systems, relying on a different choice for the fundamental units, which were anyway always three in number and mechanical in nature. The I Congrès International des Electriciens, held in Paris in 1881, during the International Exposition of Electricity. The congress—which lasted from 15 September to 5 October 1881—was attended by approximately 250 delegates representing 28 countries. Among them were Hermann von Helmholtz, Rudolf Clausius, Gustav Kirchhoff and Ernst Werner von Siemens (Germany), Ernst Mach (Austria), Lord Kelvin and Lord Rayleigh (England), and Henry Augustus Rowland (United States). The importance of this congress can be understood if we remember that, at the time, there were 12 units of electromotive force, ten units of current intensity, and 15 units of electrical resistance used in different countries. Giorgi’s brilliant intuition was that all the difficulties could be solved simultaneously if one abandoned the absurd pretension of reducing the electromagnetic units to mechanical ones. His fundamental observation was that the group of units more used in practice—those of resistance, capacity, intensity of electric current, difference of potential, and inductance—is fully determined by the units of work and time, and one of them, independent of the choice, by the units of length and mass. The only condition is that the electrical and mechanical powers are both to be measured in watts.

What obstacles (technical, political, geographic) needed to be overcome?

The work of Giovanni Giorgi should be framed in a chaotic context. The starting points for the extension of the existing mechanical unit system generated in 1863, based on the metric system derived from the French Revolution, to the electric and magnetic ones are the well-known Coulomb and Laplace laws:

Fe = q1 q2 ro/(ke r^2); Fm = m1 m2 ro/(km r^2); Fem = m idc x r/(kem r^2),

where the qi and mi are the electric and magnetic charges and masses, respectively, ro is the unit vector along the direction joining them, and idc is an element of current of intensity i along infinitesimal segment dc. ke, km, and kem are special coefficients. Here, the convention of Kennelly is used. A fourth link between the charge and the current is given by: i = q / t . The previous three formulas link the three constants ke, km, and kem and the two electric and magnetic masses. For this reason, only two of them can be arbitrarily chosen (value and dimensions): the possible choices determine the various systems of units. In a communication to the Congress of the Italian Electrotechnical Association in 1901, and a subsequent publication in Italian and English, he proposed a solution to the problems that plagued the absolute systems, which could be summarized into the following points:

the presence of a 4π in the wrong places, i.e., where spherical symmetry is absent, is because of the values assigned to ke and km, e.g., the capacity of a plane condenser with the plates of area S, a dielectric of thickness d, and an absolute dielectric constant ε, in the CGSem system, is given by εS/(4πd), while the capacity of a spherical conductor of radius r is given by εr;

the existence of more than one absolute system, due to the freedom in the choice of the values and the dimensions of two among the constants ke, km, and kem;

the fact that, in every proposed system, some of the units were too large or too small for practical purposes—this too due to the apparently natural choice for the electromagnetic constants—forced the use of the so-called practical units, defined as their suitable multiples;

even if the mechanistic vision of the physics was in full crisis, all the systems of units in use were still built on the three fundamental mechanical units of length, mass, and time.

What features set this work apart from similar achievements?

A proposal of rationalization—i.e., the elimination of the annoying 4π factor—had indeed been made by Heaviside (1850–1925) some years before. He proposed to reformulate the Coulomb laws and assign to ke and km the values 1/(4πε) and 1/(4πµ), respectively. He even proposed some new units, which were different from the old ones by ratios of 2sqrt(π), 2, or 4π. However, the proposal, which came only six years after the international adoption of the practical units, was rejected. There was a long epistolary exchange between Heaviside and Giorgi.

References to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or citations to pages in scholarly books. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article.

G. Giorgi, “Unità razionali nell’elettromagnetismo [Rational units in electromagnetism],” Atti dell’Associazione Elettrotecnica Italiana, vol. 5, pp. 402–418, Oct. 13, 1901.

G. Giorgi, “Memoria originale dell’ing. Giovanni Giorgi [An original memoir by Giovanni Giorgi, engineer],” Il Nuovo Cimento, vol. VI, no. 5, pp. 11–30, 1902.

G. Giorgi, “Rational units of electromagnetism,” Read before the Physical Society of London, May 27, 1902.

G. Giorgi, “Rational electromagnetic units,” Electr. World Eng., vol. 11, pp. 368–370, Sept. 6, 1902.

M. Ascoli, “On the systems of electric units,” in Proc. Transactions Int. Electrical Congr., St. Louis, MO, 1904, pp. 130–141.

F. Frezza, S. Maddio, G. Pelosi, and S. Selleri, “The Life and Work of Giovanni Giorgi: The rationalization of the units of measurement system”, IEEE Antennas and Propagation Magazine, vol. 57, no. 6, pp. 152-165, December 2015.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

E. Kennelly, “Adoption of the meter-kilogrammass-Second (M.K.S.) absolute system of practical units by the international electrotechnical commission (I.E.C.), Bruxelles, June 1935,” Proc. Natl. Acad. Sci. USA, vol. 21, no. 10, pp. 579–583, 1935.

Resolutions of the International Congress of Electricians, Paris, 1881.

W. Weber, “Elektrodynamische Maassbestim mungen über ein allgemeies Grundgesetz der elektrischen Wirkung,” in Abhandlungen bei Begründung der Königl. Sächs. Gesellschaft der Wissenschaften am Tage der zweihundertjährigen Geburtstagfeier Leibnizen’s herausgegeben von der Fürst, Leipzig, Germany: Jablonowskischen Gesellschaft, 1846, pp. 211–378.

W. Weber, “Elektrodynamische Maassbestim mungen, Insbesondere Widerstandsmessungen,” in Abhandlungen der Königl. Sächs. Gesellschaft der Wissenschaften, mathematisch-physiche Klasse 1, Leipzig, Germany: Jablonowskischen Gesellschaft, 1850.

W. Weber, “Messungen galvanischer leitungs widerstände nach einem absoluten masse,” Annalen der Physik, vol. 82, pp. 337–369, 1851.

P. J. Nahin, “Oliver Heaviside,” Sci. Amer., vol. 262, pp. 80–87, June 1990.

O. Heaviside, Electromagnetic Theory. London: The Electrician Printing and Publishing Co., vol. 2. 1899.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).