Marcello Stefano Pirani (July 1, 1880 – January 11, 1968) was a German

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

known for his invention of the Pirani vacuum gauge, a

vacuum gauge {{Cat main, Vacuum system Vacuum Systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its bo ...

based on the principle of heat loss measurement. Throughout his career, he worked on advancing lighting technology and pioneered work on the physics of gas discharge.

Biography

Marcello Pirani was born on July 1, 1880, in

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

. Starting in 1899, he studied

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

at the

University of Berlin The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

. In 1903, he was granted a

PhD A Doctor of Philosophy (PhD, DPhil; or ) is a terminal degree that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the deg ...

for his measurements of the

dielectric In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric ...

constant of solids in the group of Emil Warburg. He then moved to the

Technische Hochschule A ''Technische Hochschule'' (, plural: ''Technische Hochschulen'', abbreviated ''TH'') is a type of university focusing on engineering sciences in Germany. Previously, it also existed in Austria, Switzerland, the Netherlands (), and Finland (, ) ...

in Aachen (now

RWTH Aachen University RWTH Aachen University (), in German ''Rheinisch-Westfälische Technische Hochschule Aachen'', is a German public research university located in Aachen, North Rhine-Westphalia, Germany. With more than 47,000 students enrolled in 144 study prog ...

) as an assistant at the Physikalischen Institut of this university. In 1904, he joined the

light bulb Electric light is an artificial light source powered by electricity. Electric Light may also refer to: * Light fixture, a decorative enclosure for an electric light source * ''Electric Light'' (album), a 2018 album by James Bay * Electric Light ( ...

factory (''Glühlampenwerk'') of

Siemens & Halske Siemens & Halske AG (or Siemens-Halske) was a German electrical engineering company that later became part of Siemens. It was founded on 12 October 1847 as ''Telegraphen-Bauanstalt von Siemens & Halske'' by Werner von Siemens and Johann Geor ...

AG in Berlin, where he remained for the next fifteen years. At the age of 25, in 1905, he was promoted to head of the development lab of the light bulb factory. In 1906, he made his most important invention with the development of a new type of

that today bears his name, the Pirani gauge. It is based on measuring the pressure dependence of heat loss from a hot wire by heat transfer to the surrounding gas and walls. In particular, it employs the change in resistivity of the heated wire (in Pirani's original work consisting of

tantalum Tantalum is a chemical element; it has Symbol (chemistry), symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductility, ductile, lustre (mineralogy), lustrous, blue-gray transition ...

and

platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...

; today,

tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...

, platinum, and

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

are commonly used) with temperature to determine the heat loss. Its useful measurement range lies within 10⁻⁴

mbar The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea ...

up to 1000 mbar. Four years later, he finished his habilitation on optical measurements of high temperatures and studies on the relationship between temperature and emissivity of hot solids and becomes private docent at the

in Charlottenburg (now

Technische Universität Berlin (TU Berlin; also known as Berlin Institute of Technology and Technical University of Berlin, although officially the name should not be translated) is a public university, public research university located in Berlin, Germany. It was the first ...

). During the

First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, he enlisted in the army to deal with scientific-technical problems such as

wireless telegraphy Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using electrical cable, cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimenta ...

. In 1918, Pirani was promoted Titular-Professor at the

TU Berlin Tu or TU may refer to: Language * Tu language * Tu (cuneiform), a cuneiform sign * ''tu'' or ''tú'' the 2nd-person singular subject pronoun in many languages; see personal pronoun * T–V distinction (from the Latin pronouns ''tu'' and ''vos'') ...

-Charlottenburg. One year later, he co-founded the Deutsche Gesellschaft für Metallkunde (German society for metal science) in Berlin. From 1919 to 1936, he worked for the newly formed

Osram OSRAM Licht AG is a German company that makes electric lights, headquartered in Munich and Premstätten (Austria). OSRAM positions itself as a high-tech photonics company that is increasingly focusing on sensor technology, visualization and trea ...

company. As head of the scientific-technical bureau, he was in charge of coordinating and pushing scientific work in the field of light bulbs of the three founding companies

AEG The initials AEG are used for or may refer to: Common meanings * AEG (German company) ; AEG) was a German producer of electrical equipment. It was established in 1883 by Emil Rathenau as the ''Deutsche Edison-Gesellschaft für angewandte El ...

and the Auergesellschaft. In this time fall his pioneering contributions to the advancement of lighting technology, in particular in the field of

gas-discharge lamp Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionization, ionized gas, a plasma (physics), plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and x ...

s: In 1922, he was named außerordentlicher Professor at the TU Berlin. In 1928, he became head of the Studiengesellschaft for electrical lighting of the Osram GmbH. He wrote a textbook on heat generation from electrical sources in 1930. As his mother — Clara Schönlank — was Jewish,Memoirs of Mario von Pirani
«''1936 wurde er als „Halbjude“ aus dem Staatsdienst entfernt. Er emigrierte nach London''». with the rise of the

Nazi Party The Nazi Party, officially the National Socialist German Workers' Party ( or NSDAP), was a far-right politics, far-right political party in Germany active between 1920 and 1945 that created and supported the ideology of Nazism. Its precursor ...

to power in Germany he left Germany in 1936 for England and joined the research lab of

General Electric General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the year ...

Co. Ltd. in

Wembley Wembley () is a large suburbIn British English, "suburb" often refers to the secondary urban centres of a city. Wembley is not a suburb in the American sense, i.e. a single-family residential area outside of the city itself. in the London Borou ...

. There his work focused on gas discharge lamps and high temperature resistant materials. From 1941 to 1947, he served as scientific consultant for the British Coal Utilization Research Association in

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

, working on new high temperature resistant materials involving

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

. Between 1947 and 1952, he was scientific consultant for the British-American Research Ltd., also in London. In 1953, he returned to Germany as one of the few second world war repatriates with scientific background and moved first to

Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...

and from 1955 to his hometown Berlin. In 1954, he took up a consultant position with Osram working on problems in gas discharge, glass and ceramics up to an old age. On January 11, 1968, Marcello Pirani died in Berlin.

Awards

*1933 Honorary member of the Lichttechnischen Gesellschaft *1933 Gauß-Weber-Medal of the University Göttingen *1961

Federal Cross of Merit The Order of Merit of the Federal Republic of Germany (, or , BVO) is the highest state decoration, federal decoration of the Federal Republic of Germany. It may be awarded for any field of endeavor. It was created by the first List of president ...

1. class of the Federal Republic of Germany

References

{{DEFAULTSORT:Pirani, Marcello Officers Crosses of the Order of Merit of the Federal Republic of Germany 20th-century German physicists German Quakers German people of Italian descent 1880 births 1968 deaths Jewish emigrants from Nazi Germany to the United Kingdom Academic staff of Technische Universität Berlin