Oscar A.E. Schreiber, surveyor and geodesist, was the son of the German surveyor and geodesist Lieutenant-General Oskar Schreiber and his wife Marie Mejer. He immigrated to South Africa in 1890 and did survey work of various kinds, including railway surveying in Natal. In 1895 he passed the Survey Certificate Examination of the University of the Cape of Good Hope and the next year was admitted as a land surveyor in Natal Colony. He became a naturalised British citizen that same year (1896). Later he was employed as a computer for August Hammar*, who was conducting the secondary triangulation of Natal, a project completed in 1914. Schreiber carried out much of the computational work to adjust the secondary network, based on a local Cassini-Soldner coordinate system.
In Mach 1910 Schreiber entered the civil service of Natal as assistant director (under Hammar as director) of the Trigonometrical Survey of Natal. In August 1923 he became a professional assistant in the Trigonometrical Survey Office of the Union of South Africa in Cape Town, under Dr W.C. van der Sterr*, the first director of the Trigonometrical Survey of the Union of South Africa. There he supervised the calculations relating to the primary triangulation of South Africa. He retired from the public service in 1933, but from 1931 to 1937 was a lecturer in geodesy and land surveying at the University of Cape Town.
Schreiber wrote several papers on survey instruments and their accuracy, for example, 'The Zeiss theodolite' (1925) 'A method of testing the accuracy of circle graduations' (1925), 'The Tavistock theodolite' (with W. Whittingdale, 1932), all in the South African Survey Journal, and 'An account of topographical mapping with the Wild stereo-photo camera in the Cape Peninsula' (South African Journal of Science, 1930). However, as an expert in the mathematics of surveying and geodesy most of his papers dealt with the theory of coordinate systems used in South Africa, and appeared in the South African Survey Journal during 1923-1938: 'South African coordinate systems' (1923) and a series of seven papers on 'The theory of the coordinate systems of South Africa' (1927-1938). As a result of the published work of his father he was acquainted with continental geodetic techniques. In particular he did original work in the development of the Gauss conform projection to adapt it for survey calculations, and in the calculation of extensive geodesic tables that made such survey calculations practicable. This work, much of which was carried out in his own time during his early days in Natal, enabled Dr van der Sterr to adopt the Gauss conform coordinate system for the geodetic, primary and secondary triangulations of South Africa. Schreiber's geodetic tables were eventually published after his death under the title Tables for the Gauss conform projection, Clarke 1880 spheroid (Pretoria, 1943).
Schreiber was a small and absent-minded man wearing thick-lensed spectacles. He became a member of the South African Association for the Advancement of Science in 1916. He was married to Mary Hannah Ainsworth, but they had no children.