Tks, Frederick. That would be Milligan's Ind Sig Corps, having evacuated Norfolk and vicinity and reloc upstream to estab HQ in Petersburg with stations along the James and a short distance up the Appomattox. "Signal Station" noted on OR Atlas maps 92 (1) and 100 (2), possibly referring to the one Milligan called "Gregory's farm" station, next below sta at Drewry's Bluff. If you ever come across sketch showing the station, keep my interest in mind.