Brunelleschi's mirror, Alberti's window, and Galileo's' perspective tube'

SAMUEL Y. EDGERTONhave thought to aim the instrument toward the sky? If one knewnothing a priori about the moon’s external topography, would itsgrayish blotches be seen immediately as shades and shadows ofmountain ridges? Especially if the observer, like all people before1610, was already certain such blotches had something to do withthe moon’s translucent internal composition?Perhaps Galileo surely made some illustrations right there onthe spot as he stared at the moon from atop the San GiorgioMaggiore campanile in Venice. While none of these have survived,we are in possession of seven finished sepia studies, which I believewere done later, based on his first ad hoc sketches. These smallfinished wash drawings, four of the waxing and three of the waningmoon, are still preserved on two sides of a sheet of artist’s water-colorpaper in the Biblioteca Nazionale in Florence (Figure 16). All werecertainly done by someone well-practiced in the manipulation ofFigure 16170 História, Ciências, Saúde – Manguinhos, Rio de Janeiro