A tide clock is a type of clock that is designed to measure the approximate time of the tides. It is not actually measuring the tides themselves, but rather the position of the moon in its orbit around the Earth.
The gravitational pull of the moon causes the tides to rise and fall, and the position of the moon in its orbit has a predictable effect on the timing and height of the tides. A tide clock is calibrated to this cycle, and can provide an indication of when the tide is likely to be high or low based on the position of the moon.
Tide clocks are often used by fishermen, boaters, and other people who need to plan their activities around the tides. They can also be used by beachcombers and other outdoor enthusiasts who want to know when the tide is likely to be at its lowest point so they can explore the shoreline.