1565—The Low Countries
Musica, an engraving by Dutch artist Cornelis Cort from a series called the Seven Liberal Arts (after works by Frans Floris) includes a small trombone hanging on a wall in the background. It is nearly impossible to tell, as artists are often less than literal, but the instrument could be an alto trombone. Compare it proportionally, for example, with the other instruments nearby (see detail and full image below—click full image to expand; public domain) (Burgers 99).
