Self Winding Clock Co. Slave (Secondary) Clocks. Uncommon and very interesting.
IBM and Standard Electric Time had reliable master clock-slave clock systems. And so did the Self Winding Clock Company but not much is known about their system. The various voltages and number of pulses per minute are explained. Self Winding was well known for it's master clock connection with Western Union Time Service and Subsidiary clocks but not for it's master clock-slave clock systems.