ClipArt ETC
Intersection of lines between a circle and its polar point.

Circle Polar Point

Intersection of lines between a circle and its polar point.

"Modern dynamo with four consequent pole field magnets. In this construction the ring shaped yoke also serves as a frame; the circular form of yoke gives the least chance of magnetic leakage." — Hawkins, 1917

Multi-polar field magnet

"Modern dynamo with four consequent pole field magnets. In this construction the ring shaped yoke also…