No. 12940 Girl Reading by Sarah Johnston
Sarah Elizabeth Murphy Johnston (1811-1880) was the wife of David Claypoole Johnston and the mother of five (including Thomas, John and Sarah J.F.). She was also a flower painter.
The Payson family lived on Payson Street in Dorchester.
See the Johnston family collection at the American Antiquarian Society
https://www.americanantiquarian.org/Inventories/Johnston/introduction.htm