This collection contains letters and documents pertaining to Cope's research on the history of Charles Mason, Jeremiah Dixon, and the Mason-Dixon Line. Most of the letters are to English researchers, but included are some typescripts of original letters by Mason and Nevil Maskelyne. Cope published numerous articles on this topic, many printed by the American Philosophical Society.

This collection includes correspondence to and from Boskovic; a travel journal in Europe; and a large number of manuscripts on astronomy, hydrography, hydro-mechanics, mathematics, geometry, mechanics, and optics; and a volume of poetry.