German-born American author (1837–1900) who was the first curator of prints at the Museum of Fine Arts, Boston. Original 4.25 x 6.5 cabinet photo by Notman of Boston, twice-signed on the reverse in black ink, “S. R. Koehler,” with sentiments in German and Spanish. Some spotting and toning to the photo, two tack holes to the lower border, and light soiling and a pencil notation to the reverse, otherwise fine condition. RR Auction COA.