The Cog Boat Borne by Mercury, Hercules, Minerva and Neptune

Visible traces of the sculptor can be discerned in this freely modelled bozzetto (clay sketch) for the crowning element of a pump: fingerprints, sharp, deep grooves and tiny holes made by the sculpting tools to suggest depth, and short parallel lines from a serrated spatula to enliven the surface. These accents are comparable to hatching in drawings.