Marcello Pirani
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Marcello Stefano Pirani (July 1, 1880 – January 11, 1968) was a German physicist, known for his invention of the Pirani vacuum gauge, a vacuum gauge based on the principle of heat loss measurement. Throughout his career, he worked on advancing lighting technology, and also pioneered work on the physics of gas discharge.
[edit] Biography
Born July 1, 1880 in Berlin.
From 1899, Marcello Pirani studied Mathematics and Physics at the University of Berlin. In 1903, he was granted a PhD for his work on measurements of the dielectric constant of solids in the group of Emil Warburg. He then moved to the Technical University of Aachen as an assistant at the Physikalischen Institut of this University.
In 1904, he joins the light bulb factory (Glühlampenwerk) of Siemens & Halske AG in Berlin where he will remain for the next fifteen years. At the age of 25, in 1905, he is promoted head of the development lab of the light bulb factory.
In 1906, he makes his most important invention with the development of a new type of vacuum gauge that today bears his name, the Pirani vacuum 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 and Platinum, today, Tungsten, Platinum or Nickel is commonly used) with temperature to determine the heat loss. Its useful measurement range lies within 10-4mbar up to 1000mbar.
Four years later, he finishes 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 Technical University Berlin-Charlottenburg. During the first world war, he enlists in the army to deal with scientific-technical problems such as wireless telegraphy.
In 1918, he is promoted Titular-Professor at the TU Berlin-Charlottenburg. One year later, he co-founds the Deutsche Gesellschaft für Metallkunde (German society for metal science) in Berlin.
From 1919 to 1936, he works for the newly-formed Osram 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 Siemens & Halske, AEG and the Auergesellschaft. In this time fall his pioneering contributions to the advancement of lighting technology, in particular in the field of gas-discharge lamps: In 1922, he is named außerordentlicher Professor at the TU Berlin. In 1928, he becomes head of the Studiengesellschaft fpr electrical lighting of the Osram GmbH. He authors a textbook on heat generation from electrical sources in 1930.
As a professing Quaker, he leaves the national socialist Germany in 1936 for England and joins the research lab of General Electric Co. Ltd. in Wembley. There his work focuses on gas discharge lamps and high temperature resistant materials. From 1941 to 1947, he serves as scientific consultant for the British Coal Utilization Research Association in London, working on new high temperature resistant materials involving carbon. Between 1947 and 1952, he is scientific consultant for the British-American Research Ltd., also in London.
In 1953, he returns to Germany as one of the few second world war repatriates with scientific background and moves first to Munich and from 1955 to his hometown Berlin. In 1954, he takes 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 dies in Berlin.
