Tide clock - Matt black case

Tide is the effect of the gravitational attraction of the moon, and in a lesser degree of the sun, on the waters of the earth, by which they tend to become heaped up at the point below the moon, and at the opposite point to this, so that twice in each lunar day there is an alternate inflow and outflow on the shores, modified by local configurations.

The time from the sun’s highest position one day until the next day’s highest position is 24 hours.
The period from the moon’s highest position one day until the next day’s highest position is 24 hours 50 minutes and 28 seconds. 

A tide clock’s day and night accordingly lasts 50 minutes and 28 seconds longer than a normal day and night. So the tide clock’s hand will use 12 hours 25 minutes and 14 seconds making one round, whereby the hand is showing precisely the cyclus of the tide.