Andrew Ellicott (January 24, 1754 August 28, 1820) was a U.S. surveyor who helped map many of the territories west of the Appalachians, surveyed the boundaries of the District of Columbia, continued and completed Pierre (Peter) Charles L'Enfant's work on the plan for Washington, D.C., and served as a teacher in survey methods for Meriwether Lewis.
Andrew Ellicott was born in Buckingham Township, Bucks County, Pennsylvania as the first of nine children of Joseph Ellicott (1732 1780) and his wife Judith (née Blaker or Bleaker, 1729 1809). The Quaker family lived in modest conditions; his father was a miller and clockmaker. Young Andrew was educated at the local Quaker school, where Robert Patterson, who later became a professor and vice provost at the University of Pennsylvania, was his teacher for some time. Andrew was a talented mechanic like many of the family and showed some mathematical talent, too.
Read Andrew Ellicott Douglass and the Giant Sequoias in the Founding of Dendrochronlogy by Donald J. McGraw, free from treeringsociety.org.