Andrew Ellicott

Photo: Library of Congress

On April 19, 1803, Meriwether Lewis arrived in Lancaster, Pennsylvania, to begin his studies with Andrew Ellicott. Considered the nation’s premiere astronomer, Ellicott would provide the explorer-to-be with the necessary skills and principles of astronomical observations and surveying, which could be applied to the techniques of navigation.

Ellicott taught mathematics in Baltimore prior to the Revolutionary War. Afterwards, he surveyed large areas where borders were still being established, including the Mason-Dixon line between Pennsylvania and Maryland. He made the first topographical study of the Niagara River and falls, and between 1791 and 1793 he surveyed the “Federal City,” redrawing Pierre L’Enfant’s design.

A member of the American Philosophical Society, Ellicott had knowledge of the frontier and experience dealing with Native peoples, which made him an ideal person to train Lewis. They set to work on April 20, using a sextant, chronometer, and other instruments for recording celestial movements. The practice sessions took longer than anticipated, and it was not until May 7 when Lewis was able to move on to Philadelphia and his studies continued with other scientists.

Ellicott continued to accept surveying commissions, but was seldom rewarded adequately for his work. As such, he suffered financially. In 1813, he accepted a post as professor of mathematics at the young West Point Academy. He died at West Point on August 20, 1820 at the age of 66.