Robert Logan Horton, 85, an electrical engineer with the Stone & Webster Engineering Corp. and then the District of Columbia government before retiring in 1970, died Thursday at Fairfax Hospital. He had cancer. b

Mr. Horton was a native of Scott County, Va. During World War I, he served aboard submarines and as an aide to Thomas Alva Edison, the famous inventor, who was president of the Naval Consulting Board during the war.

Following the war, Mr. Horton studied electrical engineering, then spent 30 years as an electrical engineer with Stone & Webster before retiring to Annandale where he has lived since 1958. He then worked for the D.C. government until retiring a second time.

He was a member of the Friendship United Methodist Church in Falls Church, and taught adult classes there. He also had been active in the Republican Party in Nothern Virginia and had been a party precinct chairman in Falls Church.

Survivors include his wife, Mayme Lee Horton of Annandale; four sisters, Vivian Woods of Bristol, Va., Maude Lacey of Kingsport, Tenn., Mary Buchannon of Bradenton, Fla., and Ann Horton of Clinchport, Va., and three brothers, Ernest of Longview, Tex., Frank, of Clinchport, and J. P. Horton of Big Stone Gap, Va.