Series II. Professional and Business Papers has been divided into two subseries. Subseries A. Political Papers is largely comprised of letters received from mentors John Varnum and Leverett Saltonstall. Many of the letters from 1819 and the early 1850s document the concerns of local residents on the issues of slavery and secession. The Whig Convention papers illustrate the election of delegates from twenty-one Essex County townships to a convention of National Republicans (Whigs) held in Ipswich, Massachusetts in 1831. Subseries B. Legal and Business Papers document the close relationship between Duncan's legal work as a probate lawyer and Justice of the Peace and his real estate investments in eastern Massachusetts and New Hampshire. The correspondence contains information on Duncan's management of various real estate transactions, as well as material concerning the Boston and Maine railroad. The real estate transactions are largely deeds and agreements in which Duncan conducted business for himself or on behalf of clients. The papers of the Haverhill Bridge document the activities of the proprietors of the bridge and associated land transactions and disputes. The railroad corporation materials contain notes on the status of a number of railroads, including the Haverhill and Andover, Eastern, Western, and the Andover and Wilmington lines. The Eliphalet Webster account papers are financial statements for a store owned by Duncan and managed by Webster.