The idea was to alternate which side of the points would be connected to ground by reversing the current flow through the points at every startup. Eventually, the factory engineers realized that by using the correct capacitance condenser, metal transfer across the points could be minimized and the current reversing was not needed. The polarity reversing switch just adds unnecessary complexity to what should be a simple on/off switching circuit.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!