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 TERTIA.

Optica delineatio rectanguli, alterâ parte longioris.

Latitudo BC rectanguli A ponatur in linea plani, adhibito circino, vel chartulâ complicatâ; & ex punctis B & C fiant visuales ad O, punctum perspectivæ. Tum papyro ex altera parte iterum complicatâ, notetur longitudo CD rectanguli; ducendo tum rectam DE ad punctum distantiæ, tum rectam FG parallelam ad BC, quæ complebit opticam delineationem rectanguli.

Altera figura ostendit complicationem cruciformem papyri, quæ adhiberi potest in delineandis rectangulis, seu latitudo eorum sit major longitudine, aut vice versâ; seu latitudo & longitudo sint æquales.

The Third Figure.

The Delineation of an Oblong Square in Perspective.

Let the Breadth BC of the Square A, be plac’d in the Line of the Plan, by the Compass, or a folded Paper, and from the Points B and C, make the Visuals to the Point of Sight O. Then fold your Paper cross-wise, and mark CD the Length of the Square, drawing the Line DE to the Point of Distance, and the Line FG parallel to BC, which will complete the Optick Delineation of the oblong Square.

The other Figure shews the Folding of the Paper cross-wise, which is of ready use in delineating Squares, whose Breadth exceeds their Length, or vice versâ; or whose Length and Breadth are equal.