Some of the early electric clocks had an indicator that the mains had been interrupted and the time would be incorrect so allowing the owner to re-set the time. However many movements were not self starting and so the time being obviously wrong could be corrected. It would be easy to notice a clock with a 'seconds' hand that had stopped. Others were made with a 'wavy line' indicator in the top or bottom part of the dial - also identify the clock had stopped.
Starting a synchronous movement is normally (not exclusively) done by a combined hand setting/starting button. When the button is released the action shifts a small lever that acts on the motor pinion and spins the motor in the correct direction to start it. Therefore a quick release works best at starting a Bijou movement and a slow release best at starting a de luxe.
REPAIR AND OVERHAUL
SYNCHRONOUS WALL CLOCKS &
CONVERTING SYNCHRONOUS CLOCKS TO LOW VOLTAGE
ELECTRIC CLOCK CARE
ELECTRIC CLOCK MANUFACTURERS
STARTING A SYNCHRONOUS ELECTRIC CLOCK
BENEFITS OF A MAINS ELECTRIC CLOCK
SYNCHRONOUS CLOCK ACCURACY
ORIGINAL CLOCK INSTRUCTIONS