Resonance Time

The problem of telling the time in the dark has already been solved by illuminated dials, but if you're buying a mechanical watch in this age of quartz I think it's reasonable to expect a mechanical solution.

If you press a ticking watch against your ear you will hear not only the tick, but a number of reverberations from the various springs, excited by the energetic tick. It's probably possible to determine how wound-up the watch is by the pitch of these resonances.

I propose purposefully fitting a reverberation plate inside the watch. A wiper or dampener is attached to the hour hand spindle which makes the resonant pitch correspond to the current time.

It could be discrete, by cutting slots in the plate, and possibly a drone (fixed pitch reverberator) could be added, since intervals are often easier to identify than absolute pitches.

This would be very easy to manufacture, much simpler than a chiming mechanism and it would be so subtle than most people wouldn't even notice it. But what a swish way to tell the time.