Carsten Niebuhr (March 17, 1733- April 26, 1815) was a German mathematician, cartographer, surveyor, explorer, and astronomer active in Denmark and the Middle East in the second half of the 18th century. Neibuhr is best known contributions to the ill fated 1761-67 Royal Danish expedition to Arabia where he employed revolutionary astronomical and hydrographic surveying techniques to produced advanced maps of the Nile Delta, Red Sea, Persian Gulf and Shat el Arab. The expeditions encountered a series of misfortunes associated with disease and dwindled until only Neibuhr remained. As the only surviving member of the expedition he continued to Bombay and then returned overland via Muscat, Bushire, Shiraz, and Persepolis to Denmark. Neibuhr used Tobias Mayer's lunar distance method for determining longitude, a technique that would later be adapted by Cook, Vancouver, and other great marine surveyors of the late 18th century.