One of his specialities, for which he was also well known, was historical material relating to the West Indies, especially the Lesser Antilles. He helped build a number of institutional and private rare book collections, including the Walter Beinecke, Jr., collection of James M. Barrie at Yale University, the Beinecke collection of the Lesser Antilles now at Hamilton College, the J. K. Lilly collection of 19th-century American literature now at Indiana University, the collection of 18th and 19th century British colorplate books given by Paul Mellon to Yale University, and the Sinclair Hamilton collection of early American illustrated books now at Princeton University. He was a founding member of ABAA, on the Board of Governors of which he served several terms and of which he was elected vice president. He was also a founder of that organizations Bookman's Benevolent Fund. His son Newcomb was killed in Russia in 1966.
Funeral arrangements are private.