Last night, out of curiosity, I used a magnifying glass to try to read the signature of the portrait. Since Joseph's father-in-law, Joseph Biays, and aunt-in-law (?), Sarah Jackson, both had their portraits done by Rembrandt Peale which are in the Smithsonian, I wondered if Peale may have done this as well. I could only make out "H. Elo???". So I located a collector of miniature portraits on the web from New Zealand and sent him photos of it and asked if he might know the artist. He responded within hours. The artist was Jean Pierre Henri Elouis (1755-1840), from France who emigrated to America for some years around 1790 and where he called himself Henry Elouis. He returned to France in 1807 where he remained for the rest of his life.