Added the below caption and images to the Trombone History Timeline (19th century, 2nd half).

c. 1875—Grass Valley, California: An engraving for a poster promoting a performance of the Berger Concert Troupe in Grass Valley, a mining town in Nevada County, California, includes a woman holding a trombone (see first image below; public domain). A photograph from the time may have served as a model for the engraving (see second image below; public domain) (NYPL Digital Collections).