Coil or Magneto
from: Practical Motorist, February 1936

Unfortunately the original document was not a good quality reproduction, hence the diagrams are unclear.

PM Coil 1a

From: Practical Motorist,July 1937

PM Coil 2a

PM Coil 3a

See also:

Automatic Ignition Cotrol

Centrifugal Ignition Control

Coil Ignition

Coil or Magneto

Contact Points

Ignition OK?

Tracing & Rectification of Ignition Troubles