University of Waterloo, Waterloo, Ontario: 16mm.
"This film begins by showing that a triangle intersecting a square plane forms a line. When the plane and triangle are viewed from the edge, the line appears as a point. Orthographic views, including the back view of the line, are shown. By changing the orientation of the profile view so that it is parallel to the line as viewed from the top and by maintaining the back view perpendicular to the profile plane, one can develop the first auxiliary. By then inclining the back view perpendicular to the line seen from the first auxiliary view, one can develop the second auxiliary—the projection of the line as a point."