S. Boardman Downing was active/lived in Pennsylvania. S Downing is known for sculpture.
Biography S. Downing
"S. Boardman Downing, listed as artist or sculptor in Philadelphia directories from 1860 to 1864, exhibited at the Pennsylvania Academy from 1858-1860. This is most likely the same artist who is recorded in the 1860 census as Sabien B. Downey, sculptress, age 20, native of Pennsylvania, since both are recorded as residing with Delia Downing or Downey (a native of MA, age 48, $1,000 in personalty). Also appears as Sabien B. Downey. "
Peter Hastings Falk, Editor, Who Was Who in American Art