This clock is a great example of taking a very simple mechanism and making it a lot more interesting using a bit of ingenuity. The Tide Clock uses an ordinary circular clock mechanism, and adds a linkage to make an indicator slide up and down. As the indicator reaches the top or the bottom, it slows down; towards the middle of its travel, it speeds up.

This is, as its creator explains, the sine function at work, and it’s also exactly how the tides move.