Andrew Adgate "Ad" Duer was born December 3, 1846. He was the son of John Duer and Henrietta Dorsey Adgate. He resided in Baltimore and worked as a representative for the Hardware Company John Duer and Sons. He married Margaret "Madge" Lewis Marshall, and they had nine children: Henrietta, Francis, Isabelle, Madge, Agnes, John, Thomas, Adgate and Dudley. He died in 1892 at the age of 46. Margaret "Madge" Lewis Marshall was born in 1850. She was the daughter of Col. Thomas Marshall and Maria Barton, and the great granddaughter of Chief Justice John J. Marshall (b.1755). She married A. Adgate Duer, and together they had nine children. She died in c1939.