Here’s an Ithaca perpetual (double dial) calendar clock I repaired. The case is walnut, the top dial gives the time, and the lower dial gives the month, date and day of the week. It keeps track of the leap year cycle, and will give February 29 days every four years.
Note: there are exceptions to every four years being a leap year. If the year is an even century, it is not a leap year, unless the year is divisible by 400. Thus, 2000 was a leap year, but 1900 was not. The next leap year will be 2024.
Wm. L. Gilbert Clock Co. made the movement for Ithaca. It strike the hour and half hour, and has the date stamp “1906”.



Repair job 8680. The time mainspring was a replacement that was too strong. The strike mainspring was the original 3/4 x 0.017 to 0.0173″ thick. I replaced both springs with the MS298: 11/16 x 0.015 x 108″ spring. This made the striking slightly slow, but it runs for about two weeks on a winding.
I polished the pivots and installed 11 bushings. This movement has the large factory-installed bushings for the second gears, I’ve seen this on other makers’ movements for Ithaca also (like Noah Pomeroy). The minute hand was a replacement that didn’t match the hour hand, I installed a better-looking replacement.
Luckily, these calendar mechanisms are vary reliable and usually don’t need repair (as long as no one has oiled it or tinkered with it. The only adjustment needed in this case is adjusting the lift so the date and day change reliably.
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