License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Stefano della Bella. A mortar without a carriage lying on the ground to the right, soldiers firing cannons creating clouds of smoke in the background, from "Equipment needed for Fortification" (Recueil de diverses pièces très nécessaires à la fortification), ca. 1638–43. The Metropolitan Museum of Art.