Died: 6 February 1992 in Bucharest, Romania

Caius Iacob was born two years before the start of World War I. His father, Laza Iacob, was a professor of law at the University and was much involved in the development of modern Romania. World War I was a decisive event in this development for, in 1916, Romania entered the war on the side of the allies on the promise from France and Britain that Romania would gain territory (particularly Transylvania). Laza Iacob was one of the official delegates at the Union of Romania conference to set this up on 1 September 1918.

Caius attended the lycée "Moise Nicoara" in Arad for three classes, then moved to the lycée "Emil Gojdu" where he spent his final year. Graduating from school at the age of sixteen, having obtained the highest marks of anyone in the whole of Romania in the baccalaureate examination, he entered the University of Bucharest in 1928. When he graduated with his licence in 1931 he was still only nineteen years of age. He then went to Paris to continue his studies and at the Faculty of Science his thesis was Henri Villat. Iacob submitted his thesis Sur la determination des fonctions harmoniques conjuguees par certaines conditions aux limites. Applications a l'hydrodynamique and defended it before a committee at the Sorbonne on 24 June 1935.

Returning to Romania, Iacob decided that he wanted a career in higher education and scientific research. He was appointed as an assistant at the Scola Politehnica at Timişoara in 1935. On 15 March 1938 he was named assistant in the Faculty of Science at the University of Cluj. At Cluj he worked in the departments of Analytic Geometry, descriptive Geometry, Analysis, and Complex Functions. We should say a little about the history of the University of Cluj since this is relevant to Iacob's career. The University in Cluj, which had been named the Franz Joseph University since 1881, became a Romanian institution and was officially opened as such by King Ferdinand on 1 February 1920. (The Hungarian university in Cluj moved first to Budapest, then to Szeged.) The university in Cluj was named King Ferdinand I University and it was at this university that Iacob was appointed in 1938. However in 1940, after the start of World War II, the Hungarian university was moved back from Szeged to Cluj, and the Romanian university in Cluj moved to Sibiu and Timişoara. In 1945, following the end of World War II, the Romanian University returned to Cluj and was named Babes University (after the Romanian natural scientist Victor Babes). Parts of the Hungarian university in Cluj moved back to Szeged, while that part which remained in Cluj was named the Bolyai University (after János Bolyai).

Now Iacob had moved away from Cluj in 1939 when he was appointed as an assistant in the Faculty of Mechanics at Bucharest University, but he returned to the University of Cluj in 1942 when he was appointed as a lecturer in the Department of General Mathematics. At this time D V Ionescu was Dean of the Faculty but Ionescu, who was professor in the Department of Mechanics, moved to the Department of Analysis in 1943. Following this Iacob was named professor in the Department of Mechanics on 30 December 1943. From this time he worked in Cluj until he was named professor of mechanics in the Department of Mechanics and Physics at the University of Bucharest on 14 October 1950. In 1952-53 he was vice-rector of the University but he was not to end his association with Cluj for he returned there for the two years 1967-69. He came back to Cluj into a new section of Fluid Mechanics which had just been set up and there he introduced an aerodynamics course. Even though he was only back at Cluj for a comparatively short period, he organised research seminars on fluid mechanics and many members of the existing staff became his doctoral students at this time. After returning to Bucharest, he worked there until he retired in 1982.

The scientific biography [4] was written to celebrate Iacob's 60^th birthday. Already in this work 152 publications are listed. We give just a flavour of his work by listing a few: On some harmonic functions of two variables (Romanian) (1940), On a necessary condition for the transformation into satellites of the planet of bodies projected from a planet (Romanian) (1949), Théorie de l'aile angulaire aux vitesses supersoniques (Romanian) (1950), Sur quelques écoulements lents des fluides visqueux (Romanian) (1953), and Recherches sur la théorie des mouvements coniques supersoniques (Romanian) (1954).

Iacob's most important monograph was Mathematical introduction to the mechanics of fluids (Romanian) which was published in 1952. This contained material on classical hydrodynamics and compressible-flow theory which Iacob had included in his lecture courses at Cluj during 1947-49 and also material which he had delivered at conferences in Bucharest in 1950. J H Giese writes:-

It deals almost entirely with steady irrotational non-viscous flows. Except for chapters on determination of velocity fields corresponding to given vorticity fields, on Prandtl's lifting-line theory of wings of finite span, and sections on conical supersonic flow fields, the problems considered are strictly two-dimensional. As the title implies, the point of view is exclusively theoretical; there is no extended consideration of calculation of aerodynamic coefficients, practical treatment of wind-tunnel corrections, etc. The author's more than twenty years' research on boundary-value problems for plane harmonic functions is reflected in a thorough account of the potential-theoretical background for the solution of plane incompressible-flow and linearized compressible-flow problems.

This book by Iacob consisted of over 800 pages, but a French version of the text Introduction mathématique à la mécanique des fluides (1959) contained over 1200 pages. His thesis advisor Henri Villat wrote a preface to this work. One further book by Iacob deserves mention, namely Applied mathematics and mechanics (Romanian) which he published in 1989 as a book for secondary school mathematics teachers. A review of the text explains its level and aims:-

One should emphasize, however, that the level of presentation is quite challenging for the "normal" high-school student, so the textbook is more appropriate for special "after-school" seminars for above-average students interested in mathematics and mechanics, rather than for usual classroom lectures. The author's declared goal is to stimulate both the teacher and his disciples to go beyond the material usually offered in courses on geometry and mechanics.

Iacob received many awards and honours for his contributions. He was awarded the prestigious mechanics prize Henri de Parville in 1940 by the Academy of Sciences in Paris. His important book on fluid mechanics earned him the State Prize for the period 1951-52. He was elected a corresponding member of the Romanian Academy of Sciences on 2 July 1955, becoming a full member on 21 March 1963. On 19 March 1980 he was elected President of the Mathematics Section of the Academy and he continued to hold this position until his death. The Institute of Applied Mathematics of the University of Bucharest was named the "Caius Iacob Institute".

Books:

1. L Dragos, Le professeur Caius Iacob - l'activité scientifique, Rev. Anal. Numér. Théor. Approx. 21 (2) (1992), 103-104.
2. L Dragos, A celebration of the great accomplishments of the Academician Caius Iacob on his 70th birthday (Romanian), Gaz. Mat. (Bucharest) 87 (9-10) (1982), 337-338.
3. L Dragos, A Georgescu and D Homentcovschi, L'académicien Caius Jacob (à l'occasion de son 70e anniversaire), Rev. Roumaine Math. Pures Appl. 27 (3) (1982), 265-268.
4. St I Gheorghita, Academician Caius Iacob, Gaz. Mat. Ser. A 77 (1972), 101-114.
5. IN MEMORIAM - Caius Iacob (1912-1992), Romanian Astronomical Journal 2 (1992), 1.
6. Obituary : Caius Iacob (Jacob), 1912-1992, Libertas Math. 12 (1992), 202.
7. A Pál, 'Cluj periods' of the didactic and scientific career of Professor Caius Iacob, Seminar on Mechanic ('Babes-Bolyai' Univ., Cluj-Napoca, 1992), 53-58.
8. E Roman, Quelques notes sur l'écho de l'oeuvre de Caius Jacob, Mathematica (Cluj) 24(47) (1-2) (1982), 5-7.