Chapter III: THAT from the Disposition of the Perspective-Plans and Uprights,

with respect to the finish’d Pieces in the Twelfth and many following Figures, you would observe, with what Dispatch the said Pieces may, without the Help of Compasses, be delineated by your Drawing-Square; _viz._ the Perpendiculars from the Perspective-Plan, and the level Lines from the Perspective-Upright, or Section.