The collection consists of works, correspondence, financial records, photographs (including tintypes), a map, and printed matter of Maclay. The collection contains an autograph and typed manuscript of his novel A Budget of Letters from Japan (1886), the autograph manuscript of an unpublished novel, The Kingdom of New York, and two autograph manuscripts of articles, "The Anti-Suffrage Case" and "A Few Leaves from a Globe Trotter's Diary" (1878). There is also correspondence between Maclay and his brother, Robert Hall Maclay, a merchant in Tientsin, China, in which Robert describes his life in Tientsin; and a a sixteen page autograph manuscript report by Robert Hall Maclay sent to Russell & Co., publishers in Shanghai, of his journey to Chihli, Honan and Shantung, China, written in Peking on Jan. 12, 1875. Also included are manuscripts of travel lectures on China and Japan delivered by Maclay with accompanying photographs used to illustrate the lectures and flyers to publicize them. In addition, there are statements of account of the Maclay brothers' estates. There is also a group of glass lantern slides and negatives with images of rural scenes, urban and industrial scenes, maps, buildings and landscapes, and portraits of people in Romania, Japan, India, China, and Italy.