William Dunbar (1749-1810), Scottish-born American scientist and planter, wrote the first topographical description of the Southwest.

William Dunbar was born in Morayshire, Scotland, son of Sir Archibald Dunbar. After study at Glasgow he did advanced work in mathematics and astronomy in London until ill health forced him to seek a warmer climate. In 1771 he went to America and established a plantation in British West Florida with a partner. Plagued by misfortunes--a slave insurrection in 1775 and later plundering by Continental Army soldiers--they moved in 1792 to what is now Mississippi to start a new plantation. Applying the principles of scientific agriculture, chemical treatment of the soil, improved models of plows and harrows, and special machinery for pressing and baling cotton, Dunbar made such a success of the venture that he bought out his partner and was able to devote much of his time to scientific investigation.

Like many 18th-century gentleman amateur scientists, Dunbar's interests included astronomy, botany, zoology, ethnology, and meteorology. Appointed surveyor general of the District of Natchez in 1798, he represented the Spanish government in determining the boundaries between Spanish and United States possessions in that area. Immediately thereafter he became a United States citizen and began making the first meteorological observations in the Mississippi Valley. Dunbar attracted the attention of Thomas Jefferson, with whom he corresponded and who secured his admission to the American Philosophical Society. In 1804 President Jefferson commissioned Dunbar to explore the Ouachita River country. In 1805 Dunbar was appointed to conduct similar explorations in the Red River valley.

Among Dunbar's scientific concerns were investigations of Native American sign language, fossil mammoth bones, and plant and animal life. On his plantation he operated an observatory equipped with the latest European astronomical instruments. His particular concern was the observation of rainbows, and he was the first to study the elliptical type. One of his practical contributions was a method for finding longitude by a single observer, without knowledge of the time. His meteorological speculations included the theory that a region of calm exists within the vortex of a cyclone.

Dunbar corresponded with American and European scientists. He also served as chief justice on the Court of Quarter Sessions and as a member of the Mississippi territorial legislature. His most important writing was the first topographical description of the little-known south-western territory. He died at his plantation in October 1810.