Meriwether Lewis and William Clark were explorers. This collection contains the manuscript journals kept by Lewis and Clark on their travels to the source of the Missouri River and across the continent to the Pacific Ocean. There are interlineations throughout by Nicholas Biddle, who published his narrative "History of the Expedition of Captains Lewis and Clark" (1814).

An early settler and prominent citizen in the Moravian heartland near Bethlehem, Pennsylvania, Timothy Horsfield was named justice of the peace when Northampton County was formed out of Bucks in 1752, and was one of those given responsibility for the defence of the local white and Christian Indian populations during the French and Indian War. The Horsfield Papers offer a window onto the tumultuous history of northeastern Pennsylvania during the 1750s and 1760s. Comprised largely of correspondence and related documents between Horsfield, William Parsons, and provincial and military authorities, the collection includes important information on the Native tribes' actions (previously described as "Indian assaults") in the region in 1756 and 1757 and the military and diplomatic response of settlers.