Miracle Eye
When a button is labeled “miracle eye,” you expect it to do something…well…miraculous. This OP clearly wondered the same thing when they found this switch on the back of an old clock. Does it tell you the future or give you the ability to travel through time? Well, apparently, it’s nothing that dramatic.
Turning it on basically turns on a light sensor, which means the clock won’t make any chime sounds until it senses light. So, there won’t be any loud disturbances at night when people are asleep. That’s pretty cool but miraculous may be a stretch. Maybe they should have gone with a simple label like “light sensor” instead.