GIOVANNI FONTANA (attr.), Della prospettiva, ms., c. 1460
Biblioteca Riccardiana, Florence, Ricc. 2110, f. 22r
Facsimile

In this work, the functioning of eyeglasses is attributed to their magnification. However, the explanatory diagram does not show the refraction through the curved surfaces of a lens, but the magnified image of an object immersed in water.