American astronomer, surveyor, mathematician, and social critic who published almanacs 1792–97. As a free African American, he used his achievements to counter racist prejudice. In 1791 President George Washington appointed him to the survey that prepared for the establishment of the US capital, Washington, DC. A self-taught astronomer, he successfully predicted the solar eclipse that occurred on 14 April 1789. He engaged in a long correspondence with secretary of state Thomas Jefferson (who had pronounced ‘blacks’ mathematically inferior), defending the mental capacities of African Americans and urging the abolition of slavery.
Banneker was born near the Patapsco River in Baltimore County, the son and grandson of former slaves. He attended an elementary school run by Quakers that admitted African-American children, but was mainly self educated. At 15 he took over the family tobacco farm near Baltimore, devising an effective irrigation system of ditches and dams.
In 1753, at the age of 21, having studied only a pocket watch, Banneker constructed a striking clock made entirely of wood. This was the first clock of its kind in America and operated for more than 40 years. It brought him renown and enabled him to start a watch and clock repair business. After helping Maryland industrialist Joseph Ellicott to build a more complex clock, Banneker taught himself advanced mathematics and astronomy using books lent to him by Ellicott. He contradicted the forecasts of prominent astronomers by correctly predicting the solar eclipse of 1789.
Having taught himself to calculate an ephemeris (table showing future positions of planets, comets, and so on) and to make projections for lunar and solar eclipses, Banneker compiled an ephemeris for each year 1791–1804, though not all were published. When, in 1792, Jefferson said that ‘blacks’ were intellectually inferior, Banneker sent him a copy of his own acclaimed almanac, along with a 12-page letter requesting social reform to improve conditions of his ‘brethren’ (African Americans).
In 1791, aged 60, he was appointed to a three-man team of surveyors, led by Major Andrew Ellicot (Joseph Ellicott's cousin), to map out the District of Columbia. The architect in charge was fired, and took all the surveying drafts with him, but Banneker salvaged the expedition by recreating the plans from memory.
Banneker used his reputation to promote social change, in particular for an end to racism and war. He became a pamphleteer for the antislavery movement and continued his scientific studies, including a treatise on bees and a study of locust plague cycles.