Invention d'une Cascade (Design for a Cascade). Dated: c. 1755/1760. Dimensions: plate: 26.8 x 19.9 cm (10 9/16 x 7 13/16 in.) sheet: 40.3 x 25.1 cm (15 7/8 x 9 7/8 in.). Medium: etching and engraving on laid paper. Museum: National Gallery of Art, W