Posted a much better detail of this trombone sculpture in the 17th century timeline (2nd half). You can even see an extension handle on the trombone. At the bottom is a large detail not included in the timeline. For many more images of trombones on organ cases, see the Perching on the Pipes blog entry.
1697-1703—Görlitz, Germany: Eugenio Casparini’s famous organ in the church of St. Peter und Paul features decorative sculptures of angels sitting atop the pipe structure. Each angel holds 2 instruments; 2 of the angels, sitting on opposite outside edges of the structure, hold trombones while playing trumpets (see above image and facing detail) (Sonnaillon 92). For additional views, see here.