Perspective study: a square and circle projected to a point
Construction lines run from a square and a spoked circle back to a single station point at the lower left
A square and a circle divided by radii sit at the upper right, and from them straight construction lines converge toward a single point at the lower left, forming the pencil of a linear-perspective projection. Below the circle a cone or funnel and a separate ellipse show the same round figure seen obliquely. The drawing is in faint metalpoint or lead, with a little faded writing at the lower left that is not transcribed here; the Bibliothèque de l'Institut de France stamp is impressed on the sheet.
On this page
Square and circle drawn toward a station point
Straight lines lead from the corners of a square and from the rim of a spoked circle back to one point at the lower left. The construction is the converging visual pyramid by which flat figures are set into perspective.
Circle divided by radii, with cone and ellipse
The larger circle is split into equal sectors by radii like a wheel. Beneath it a cone or funnel and a separate upright ellipse repeat the circle as it would appear foreshortened.