Leopold Marquard, surveyor-general of the Cape Colony, was the son of Reverend Leopold Marquard of the Dutch Reformed Church, who came to South Africa from Germany in 1815. Leopold junior received his schooling at the South African College, Cape Town, from 1837 to 1842 (aged 11 to 16). From 1840 onwards another future surveyor-general, Abraham de Smidt*, was also a scholar there. Marquard acquired considerable proficiency in surveying and mathematics during the next few years, for in 1848 he was admitted as a land surveyor and was sent with de Smidt to check a previous survey in the Fort Beaufort Division. That same year Marquard is said to have systematised and improved a method of calculation and plotting by means of rectangular coordinates that had been initiated by the Cape surveyor Mynardus Ruysch* (Bull, 1981, p. 12, 19). Alternatively H.G. Fourcade*, himself an outstanding surveyor, credited Marquard with "the inception of the co-ordinate system of surveying practised in South Africa" (Fourcade & Whittingdale, 1930, p. 360). The method was initially developed by the French surveyor Puissant in his book Traite de Topographie, a copy of which was in Marquard's possession by 1857. According to Fourcade, Marquard improved Puissant's method in several respects: "He started from the more general case of axes independent of the meridian, altered the convention of signs to suit the clockwise order of the graduation of circles, incorporated the idea of 'angles of direction', reduced the computations to more methodical form, and devised a complete system of checks on their accuracy". The work was written up in the form of a pamphlet, The system of coordinates applied to land surveying (1862, 9 pp.) which was used by local surveyors for many years. Its success is shown by the publication of a second (improved) edition in Cape Town in 1882, and a third edition in 1895 with the title Co-ordinate geometry applied to land-surveying. Marquard also published an earlier pamphlet, The principles of proportion, or, a substitute for the fifth book of Euclid (Cape Town, 1852, 20p). Fourcade (1930, p. 360) quotes a description of Marquard by an unidentified person (perhaps De Smidt): "He was most unwearying and ingenious in simplifying and reducing work, both in the field and the office, has devised short methods of computation and a complete and perfect system of check, and ... has been at all times ready to communicate his methods to anyone who applied to him for assistance".
Marquard was appointed examiner of diagrams in the Surveyor-General's office in June 1857. In June 1858 he was appointed by the governor as one of the commissioners (the others included T. Maclear*, M. Ruysch* and G.F. Childe*) who were to ascertain and fix the size of the unit of land measure used in the Colony - a local version of the Rhynland foot. The only standards available for this purpose were two measuring rods of six Rhynland feet each that had been used by L.M. Thibault* and were later bought by Ruysch. By comparing these rods to British standards the commission found that the land unit was equivalent to 1.033 British Imperial feet (314.85mm) and renamed it the Cape foot. It remained in use as the South African unit of land measure until replaced by the metre in the nineteen-sixties.
Marquard was an examiner in science for the University of the Cape of Good Hope from 1874 to 1880 and again during 1887-1889, setting papers for the Certificate in the Theory of Land Surveying and the BA degree, in arithmetic, algebra, plane geometry, plane trigonometry and spherical trigonometry. On 23 November 1870, and again on 29 September 1872, he visited the cave known as the Heerenlogement in the Vredendal district and on both occassions engraved his name on the cave wall.
During 1879, in De Smidt's absence, Marquard served as acting surveyor-general. In that capacity he was asked to comment on a proposal by Dr David Gill* to conduct a geodetic survey of South Africa. Marquard responded by first reviewing the trigonometric surveys already completed in the Cape Colony, and the extent and accuracy of property surveys, before considering the merits of the proposal. He was not convinced that the practical advantages of the scheme (increased accuracy of property surveys, a basis for the work of civil engineers, and a framework for later mapping) would justify such an expensive undertaking and proposed a much more modest alternative project. However, with de Smidt's support Gill's proposal was accepted despite Marquard's opposition. In later years Marquard realised the long-term advantages of the geodetic survey and supported Gill on several occasions.
In 1881 Marquard served as special land commissioner in Griqualand West, and the next year was appointed secretary for lands and mines of the Cape Colony. After de Smidt's retirement in June 1889 Marquard succeeded him as surveyor-general, until his retirement in 1892. He was a foundation member of the South African Philosophical Society in 1877, and remained a member until his death in 1897. In 1895 he was honoured as a Companion of the Order of St Michael and St George (CMG). The size of his personal library is indicated by the fact that a twelve-page catalogue of a part of it was issued around the time of his death. The town Marquard in the Free State was named after his son, Reverend J.J. Marquard.