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Published on Nov 27, 2013
A homemade mechanical rolling ball clock (english, deutsche Version: http://youtu.be/wJK0AjOHbzk) The clock runs for 12 hours, driven by a weight of 2.5 kg sinking approx. 1 meter during that time..Every minute a marble is lifted up and goes down a marble run with three flipping traps that count marbles for minutes, five-minute-steps and hours. The timekeeping element is a second-pendulum with a pinwheel escapement.
The clock achieves a drift of less than 1 second per day. I have to admit that this is based on a measurement over 24 hours only, so it does not include large temperature variations. Nonetheless, I did not expect that high accurracy. But keep in mind that a pinwheel escapement is among the most precise.