used an extension of them to define the small and large Veblen ordinals. In World War II he was involved in overseeing ballistics work at the Aberdeen Proving Ground that involved early modern computing machines, in particular supporting the proposal for creation of the pioneering ENIAC electronic digital computer. He also published a paper in 1912 on the four-color conjecture. Personal life In 1908, he married Elizabeth Richardson, the sister of British physicist Owen Willans Richardson and sister-in-law of American physicist Clinton Joseph Davisson. Veblen Research Instructorship The Veblen Research Instructorship is a three-year position offered by the Department of Mathematics at Princeton University and the Institute for Advanced Study. This position was established in 1998 and offered each year to outstanding candidates in pure and applied mathematics who have received their PhD within the last three years. The Veblen instructors are Members of the Institute for Advanced Study and regular faculty members at Princeton University. The first and third year of the instructorship are spent at Princeton University and carry regular teaching responsibilities. The second year is spent at the Institute and dedicated to independent research of the instructor's choice. Books by O. Veblen Introduction to infinitesimal analysis; functions of one real variable with N. J. Lennes (John Wiley & Sons, 1907) Projective geometry with John Wesley Young (Ginn and Co., Vol. 1, 1910; Vol. 2, 1918) Analysis Situs (American Mathematical Society, 1922; 2nd edn. 1931) Invariants of Quadratic Differential Forms (Cambridge University Press, 1927) The Foundations of Differential Geometry with J. H. C. Whitehead (Cambridge University Press, 1932) Projektive Relativitätstheorie (Springer Verlag, 1933) See also Hughes plane Finite geometry Ordered geometry Hall plane of order 9 References External links Obituary and Bibliography of Oswald Veblen (also available here.) "Projective relativity theory," transl. by D. H. Delphenich 20th-century American mathematicians Topologists Geometers Ballistics experts 1880 births 1960 deaths Institute for Advanced Study faculty People from Decorah, Iowa University of Iowa alumni Harvard University alumni University of Chicago alumni Princeton University faculty American people of Norwegian descent Presidents of the American Mathematical Society Mathematicians from Iowa