The correspondence of Charles Sumner is available on a microfilm set published by Chadwyck-Healy, and includes all the letters from Sumner’s papers at Harvard as well as many letters from other institutions. Harvard faculty, students, staff, and proxies can access the film in Lamont. Researchers who are not Harvard affiliates can request the microfilm for use in Widener Library Reading Room 150.
Because it is a commercial microfilm, it is also available through a number of other libraries, and you may be able to request the reel you want through your library’s interlibrary loan department if you cannot travel to Harvard.
Because the microfilm is organized by date rather than the name of the correspondent (as are the physical papers), the documents on the reels are in a different order than the physical papers. In order to find out which reel you need, consult the reel guide.
Some of the correspondence has been digitized and can be accessed through the finding aid.
If your project requires access to the original letters, you can submit a request and include the reason you need to use the manuscripts rather than the microfilm. The curator responsible for the collection will then reply to let you know whether your request is approved.