African American scientist who authored a series of almanacs and was known for his knowledge of astronomy. After his father passed, he sold tobacco that was grown on the family farm.
He grew up on his family's farm, and studied independently while he worked on the farm.
He was a member of the team that surveyed the original border of the District of Columbia. He designed an irrigation system for his family farm, and constructed a wooden clock that was reputed to keep accurate time and ran for more than 50 years until his death.
He never married and lived on his family farm for most of his life.
He was a contemporary of Thomas Jefferson, with whom he corresponded on the issues of slavery and racial equality.