Clock light sensor
After hanging a wall clock, there’s virtually no reason to take it back down, except to replace its batteries after a few months. However, if you pay close attention to the back, you might discover a switch with the caption “miracle eye.” What is this “miracle eye” and what makes it so miraculous?
Apparently, a miracle eye is a light sensor built into fancy wall clocks. When activated, the sensor will stop the clock from chiming until it senses light. Think of a grandfather clock coo-cooing 12 times at 12 AM. If there’s no light, there’s no coo-cooing. This is a super-handy feature that would probably save you from having a grandfather-clock-induced heart attack in the middle of the night.