It is believed that the artist was Frank Sewall (1837-1915), best known as a Swedenborgian clergyman. After graduating from Bowdoin College in 1858, he traveled in Italy and was recognized for his great appreciation of the arts. Sewall held a pastorate in Washington, DC from 1889-1915. The sketches date from this period, with several signed examples also thought to be by his daughters.
From the guide to the Frank Sewall Sketches, 1891-1892., (John D. Rockefeller, Jr. Library, Colonial Williamsburg Foundation)