FYI - My great grandfather, John Wesley Perkinson, was a member of E. Graham's Battery as was his older brother (Robert Norman Perkinson). I have copies of the forms John signed for his pay, which were requested by and sent to my father from the Library of Congress. I also have a letter John Perkinson wrote in 1918, describing his experiences in the war. For the record, John Wesley Perkinson, was born in Green County, N.C. on May 14, 1846.
For anyone who would like to learn more about this artillery unit, there is a book you can read - Graham's Petersburg, Jackson's Kanawha, and Lurty's Roanoke Horse Artillery, written by Robert H. Moore, II. For some reason, I don't see references to this book but I have a copy.