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.

FIG. IV.