In Pittsburgh, Meriwether Lewis purchased a specialty “air gun” that he thought might be a good conversation piece, to help break the ice with people whose territory they would enter along the way—people whose help the party would need to complete the journey.

What was an air gun?

It was a gun that did not require gunpowder, but rather used compressed air from a tank to fire a bullet. It is the same concept as a BB gun, but with the firepower of a full rifle. It may have been manufactured in Philadelphia, but it is not entirely clear. Wherever it was made, it was an unusual gun for the time that few people (European, Indigenous, or African) would have been familiar with.

Lewis first showed it to people on Brunot Island. French settlers there were interested in it, and one man accidentally shot a woman with it (she was okay).

In October 1804, Lewis showed off the air gun to Arikara leaders Kakawissassa (Lighting Crow), Pocasse (Hay), and Toone (Eagle Feather) along the Missouri River in what is now North Dakota. Clark wrote, “after the Council was over we Shot the Air gun, which astonished them . . .”

He demonstrated the gun to Shoshone people in August 1805, and he said they found it “so perfectly incomprehensible that they immediately denominated it the great medicine.” 

Lewis showed his gun to Clatsop leader Coboway and other community members in January 1806, and he again boasted in his journal of how much his new friends liked the gun.

When on the busy Columbia River, Lewis shot his gun off for families descending the river in their canoes. He wrote, as he did of people before them, that “they were much astonished.”

(http://www.autoadmit.com/thread.php?thread_id=5538791&forum_id=2.#47732965)

The next several days are quite the comedy of errors.

Whining about the lazy locals charging the extravagant price of $1 to loan them a horse and an ox to pull their boats over the shallows.

Bought a canoe, but it leaked so bad that even after making repairs, they have to bail it out all night.

Hired a woman to bake 90 pounds of flour into bread, but then she wouldn't give it to them and they left without telling Lewis until they'd gone six miles and had to go back for it.

(http://www.autoadmit.com/thread.php?thread_id=5538791&forum_id=2.#47732968)