Lindley Fisher of Philadelphia, Pennsylvania, received 35 business letters and invoices concerning the Duncannon Iron Works between 1846 and 1851. Fisher's father, brother, and nephew worked at the factory and provided information related to its finances and to the production of nails, spikes, and bar iron. Charles William Fisher, Lindley's brother, wrote the bulk of the letters between 1846 and 1849, concentrating on the foundry's financial affairs, business relationships, and production figures. Lindley received similar letters from his father and nephew, who discussed some of the day-to-day aspects of running the iron works as well as its larger financial concerns.
In the spring of 1849, Lindley's correspondents mentioned efforts to establish a new nail-producing facility and discussed some of their business strategies, such as the possibility of offering stock. In his letter of April 2, 1851, William Logan Fisher mentioned the potential purchase of a steam engine, though he feared that the factory's debts might lead to future difficulties. In addition to his family's letters, Lindley Fisher received 3 invoices signed by Joseph S. Simpson, primarily respecting the shipment of nails produced at the Duncannon Iron Works between April and July 1849.