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

FIRST FIGURE.

An Explanation of the Lines of the Plan and Horizon, and of the Points of Sight and Distance; but more especially of this last.

For beginning any Design in Perspective, there are principally requir’d three Lines, and two Points: One Line where the Feet stand, which is call’d the Line of the Plan, or Ground-line: The second where the Eye is plac’d, call’d the horizontal Line: I shall speak of the third in the Elevations. Of the Points, one is assign’d to the Eye, the other to the Distance. The first of these is generally known, the latter not so well understood, though of great Use for giving the Removal or Depth of every Object. I shall therefore insist a while on the Explanation of the Point of Distance; and that I may more clearly shew what it is, I have chosen the Geometrical Description of a Church, which is divided into three Parts; viz. the Plan, Profile, and inner Face; in the midst of which Face one would paint a Piece of Perspective, that should seem to recede as much as the Square P in the Plan, and the Depth Q in the Profile.

On the Face CCCC, which suppose that of the Design, you see the Manner of disposing the two Lines and the two Points. HI is the Ground-line. NON is the horizontal Line, which is usually made a Man’s Height above the Ground line, as in B. The Point of Sight is O, the Point of Distance N, on which side you will. This Point N must be as far from O, as the Distance you determine to place yourself at for viewing the Depth of the Square PQ; as is exemplify’d in the Plan and Profile, where you see the thing as in its natural Position: And in them N is distant from O, as far as the Man in A is remov’d from DE; or the Man B in the Profile from FG, which is the Wall to be drawn or painted on.

If you farther and more strictly examine this Description, you’ll discern how well the Square of the Plan P, and the Elevation Q, correspond as if naturally put into Perspective on the Face CCCC, which is the Draught. For you see the Visuals which cut the Space RN in the Plan, cut the same Space TV in the Upright; and the Segment of the Visuals XZ in the Profile, answer that of YK in the Elevation; which needs no Demonstration.