Training Meriwether Lewis

Painting of Robert Patterson circa 1812

Meriwether Lewis had a variety of training to prepare for the Lewis and Clark Expedition. Thomas Jefferson, in his February 28, 1803 letter to Dr. Caspar Wistar, mentioned that Meriwether Lewis had recently learned how to calculate latitude and longitude, a skill that he and Captain Clark would use every day during the Expedition.

Calculating precise locations on the Earth is a lot easier today – just push a button on your smart phone. Back then, it took quite a lot of measurement, precise equipment and knowledge. From whom did Lewis receive his navigational education?

Initially, Jefferson taught Meriwether the basic principles. The president then sent his future explorer to meet with Andrew Ellicott, America’s leading astronomer of the day, to learn how to use the chronometer and sextant. From there, Lewis continued with Robert Patterson, a distinguished mathematician. Patterson not only provided training, but helped Lewis purchase a chronometer for the Expedition.

Patterson regulated the clock, which thereafter required winding each day at noon. Of course, Patterson knew that during the Expedition the chronometer wouldn’t always be wound precisely at noon for a variety of reasons. So other astronomical methods were taught to Lewis on how to reset the timepiece to be in sync with Greenwich.

Visit the Lewis and Clark National Historic Trail website for more stories of the Lewis and Clark Expedition.

Sources: University of Idaho, The Lewis and Clark Rediscovery Project and the Library of Congress.