Moon phase display for a clock

Moon phase display for a clock

photo of the moon phase display
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The moon is a ball of papiermaché. It is painted half black, half white, and has a black background. The wheel has 59 teeth (that is 2 x 29.5.) Every 12 hours it is nudged to the left, one tooth at a time, by the horizontal wire which is driven to and fro by an eccentric on the hour hand of the clock. On the far side of the wheel, not visible in the picture, is a pawl which prevents the wheel turning backwards.
      A lunar month is actually more than 29.5 days, (more precisely 29.530587981 days.) So the display looses about 30 seconds a day, that is, about one day in 2 ½ years.
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