Constantin Miculescu

Constantin Miculescu (September 6, 1863, Crevenicu - December 29, 1937, Bucharest) was a Romanian physician and had notable results in thermodynamics and optics. His main contribution to physics can be found even in his doctoral dissertation, in which he presented a precise method for the determination of the mechanical equivalent of heat (calories).

Between 1882-1886 he attended the Faculty of Sciences, Department of Physics and Mathematics, University of Bucharest, where he had Emanoil Bacaloglu as a teacher. He obtained a scholarship in 1888 at Paris University, obtaining a degree in science from the Sorbonne. He completed his doctor's degree with thesis Sur la determination de l'équivalent mécanique de la calorie, under the guidance of Professor Gabriel Lippmann (1845-1921), future laureate of Nobel Prize for Physics in 1908.

In 1891 he occupied as a substitute teacher the chair remained vacant after the death of Emanoil Bacaloglu, then (1894) he became Professor of molecular, acoustic and optical physics, post he occupied until his death in 1937. Since 1900, he served as inspector of education and member of the Permanent Council of the Ministry of Education. He was elected in 1904 as a member of the Governing Board of the French Physical Society and in 1909 as a member of the International Committee responsible for collecting and publishing constants in chemistry, physics and technology of the Congress of Chemistry in London. Between 1923-1928, Prof. Dr. Constantin Miculescu was Dean of the Faculty of Sciences in Bucharest.

Constantin Miculescu invented a calorimeter and an original method for accurately measuring the mechanical equivalent of heat. Hence, the 4.1857 J/calorie value was taken over as such by the international tables, becoming a fundamental constant of thermodynamics. In 1950, the value established by Miculescu has only its 4th decimal corrected, i.e. 4.1855 J/calorie. He also organized the molecular, acoustical and optical physics laboratories of the Bucharest University, where he invented in i905 a method for determining the refractive index of a prism with a microscope, then in 1910 an acoustical method for measuring the elasticity coefficient of objects.

Constantin Miculescu

Constantin Miculescu (1863 - 1937), great Romanian physicist.


He was born in Creveniciu village, Teleorman County. Outstanding student in primary school, he continue his studies at "Matei Basarab" College in Bucharest (colleague and friend of Gheorghe Marinescu, the future founder of the Romanian school of neurology), then at the Faculty of Science, Department of Physics-Mathematics in Bucharest. Here, Miculescu enjoyed the appreciation of great teachers as Spiru Haret, Marin Alexe, Emanuel Bacaloglu - the last one helped the brilliant student to obtain in 1886 a scholarship at Sorbonne University, Paris. In 1893 he obtained the PhD with a thesis in which he put forward both a sense of mathematical precision, and inventiveness.

The great physicist James Prescott Joule had determined the mechanical equivalent of the calories, a fundamental constant for physics and especially for thermodynamics. But his calculations, and other great physicists too, gave inaccurate results, with differences of up to 20% between them, and therefore unusable in practice. Miculescu instead made a totally original calorimeter, with which he measured, through a personal process, the most precise mechanical equivalent of calories: J = 4.1857, which could be included in the international tables and used as a physical constant. When, in 1950, after almost six decades, the International Committee of Weights and Measures has established the definitive value, the correction affected only the fourth decimal place (4.1855, instead of 4.1857). The 1891 experience of Miculescu became famous and is today cited not only in physics treaties, but also in school textbooks around the world, many presenting and outline its device.

Returned in Romania in 1891, when Em. Bacaloglu was dead, Constantin Miculescu was called to replace him at the Department of Physics, University of Bucharest, where he taught from 1891 until 1935, being one of founders of modern physics school in Bucharest. He developed a method for measuring the inside diameter of capillary tubes (very narrow), he created a very precise method for measuring the refractive index of a solid body with prism shape using the microscope, he developed a method for determining the coefficient of elasticity of bodies by an acoustic method...

In 1909 was elected member of the International Committee for Establishment of Physical Constants. It was the first Romanian physicist who has imposed worldwide through a major contribution - fundamental to modern thermodynamics. A prize of the Romanian Academy today bears his name, and his bust is located inside the University of Bucharest, designed by sculptor Corneliu Medrea.