Out the kitchen window the whirligig turns, metal spokes merciless as diagrams cutting the air no clothing softens, tiny gems icing the nodes where their lines intersect.

The external tangent lines intersect in the external homothetic center, whereas the internal tangent lines intersect at the internal homothetic center.

This completes the plane, because now parallel lines intersect at a point which lies on the line at infinity.

Outlying and suburban areas are served by seven private railway companies, whose lines intersect at major stations with the subway system.

Constrictions, such as at-grade crossings, where lines intersect other lines and/or roadways are eliminated.