I was completely unaware that there were any air rifles produced in the late 1700s; let alone a .46 caliber rifled barrel REPEATING air rifle which could ACCURATELY hit and put a hole THROUGH a 1" pine board at 100 yards. The link below will take you to a video which discusses the Giradoni air rifle, one of which was used by Lewis (of Lewis and Clark fame) on the famous expedition into the northwest areas of what is now the United States in about 1803.
http://www.network54.com/Forum/451309/thread/1296928404/This+is+just+to+cool+not+to+spread+around
http://www.network54.com/Forum/451309/thread/1296928404/This+is+just+to+cool+not+to+spread+around