The Henry G. McClellan papers (MC 20) cover the period 1859-1882. The collection contains correspondence, student work from McClellan’s years at RPI, notes, a few miscellaneous printed items, and McClellan’s microscope. Series 1 – Correspondence, and Series 2 – General, are both arranged chronologically. The family correspondence documents McClellan’s travels, life, and work. Many letters are from his years in Ecuador, South America, 1870-1875; these record his responses to a country where custom, geography, and political life were unfamiliar and where his work was often done under difficult conditions. Several letters are from the time of residence in California, 1875-1880, where he worked as engineer for the Pacific Bridge Company. Correspondence from Nevada, in 1880-1881, includes family news and his engineering challenges as Chief Engineer for the Nevada and Oregon Railroad. The last letter, from Tacoma, Washington in 1882 touches on his work as construction engineer on the Northern Pacific Railroad. The student material includes work for several courses McClellan took at RPI, some notes and several printed programs for academic exercises. Material concerning the RPI Class of 1869, of which McClellan was at one time treasurer has been removed to a separate file. The McClellan papers were given to RPI in two gifts by Helen MacArthur of Cambridge, New York in 1984 and 1985.