There are two marbles used in this clock that shift up and down spiral towers—one to display the hour and one to indicate the minute. The design consists of two custom-built towers housed inside of a ...

When the minute hand on a clock moves from one number to the next, it has moved 5 minutes. There are 12 numbers around the clock face, and each interval is 5 minutes… 12 × 5 = 60 minutes in an ...