"We were placed in wards of a hundred to each ward, with three rows of bunks and two men to a bunk," advised J. S. Kimbrough, Company K, 14th Georgia. an excerpt from the book 'Portals to Hell: Military Prisons of the Civil War' is one place I found and this guy was in the same unit as my G G Grandfather.
Also G.E. Ballew's brother John is listed as having signed the Oath of allegiance from Hart's Island... only problem with that is John died in 1862 from a wound at 2nd Bull Run, so it may have been George signing John's name(?). Also another little bit of a twist. John died at Warrenton Hospital and was buried in the Warrenton Cemetery, only George E. Ballew's name is engraved on the memorial.................
And last but not least I have a letter written by George Ballew in 1916 before he died telling about his war experience. Said he was captured at the last battle of Petersburg and sent to Hart's Island and then had to sign the "nasty oath of allegiance".
In my searches on the internet, I have found several of his Company that was sent to Hart's Island.