Rules and Examples of Perspective proper for Painters and Architects, etc. / In English and Latin: Containing a most easie and expeditious method to delineate in perspective all designs relating to architecture

by Andrea Pozzo

FIGURA QUARTA.

Quadratum duplex opticé.

Eodem modo construes quadratum duplex A, transferens circino, aut duplicando chartulam, latitudinem cujuscumque lineæ, ut vides in punctis 1, 2, 3, 4, 5, 6, super lineam plani in iisdem numeris, & ab istis transferes visuales ad punctum O. Postea transfer longitudinem 7, 8, 9, 10, super lineam plani in iisdem pariter numeris, & ab istis duc lineas ad punctum distantiæ E. Ubi hæ lineæ secant lineam 6, 7, O, fiunt lineæ parallelæ ad lineam plani, & quadratum conficitur; parem constructionem facies de quadrato secundo, & tertio, facilè ex dictis.