I just added the below caption and image to the Trombone History Timeline (19th century: 1826-1850).

1833—An engraving by Charles James Grant features a very unusual looking trombone. The full caption for the engraving reads, “The Royal ‘Feast of Harmony’ in Vestminster Habby: Alias ‘The Music Shop Over the Vay,’ in which John Bull Figured in the Capacity of Double Drum and Old Gery as Calfskin Thumper!!!” According to the British Museum, the images depicts the king conducting an orchestra of politicians and John Bull (meaning a typical Englishman. See below image; public domain.