How did Clark prepare for the expedition?

Meriwether Lewis who had been appointed to the rank of Captain, was designated as the expedition "scientist". Prior to the expedition, Lewis went to Philadelphia for intense training by physician Benjamin Rush, astronomer-surveyor Andrew Ellicott, botanist Benjamin Barton, anatomist Casper Wister, and mathematician Robert Patterson. For three months he was tutored in the spring of 1803.

The skills that Lewis learned would be passed on to Clark as they traveled. Prior to the expedition, Clark was in fact Lewis' superior officer and was very experienced in handling boats. Clark also served mainly as the expedition "doctor" and co-writer of the Journals. He often traded medical care for food and eventually established a reputation among the natives for his skills. Finding a man with a tumor on his thigh who couldn't walk, Clark cleansed and dressed the wound and left him some soap to wash the sore. He soon got better and as Clark says "this man assigned the restoration of his leg to me."