Just added this image and caption to the Trombone History Timeline (19th century, 2nd half) and to the collection, Backward Advances: Rear-Facing Trombones throughout History.

1869—Germany: A rear-facing trombone is featured in The Concert in the Garden Pavilion, an engraving by Capri, after an illustration by Anton von Werner (Der Trompeter von Säckingen,” 1860) (see below image; public domain).