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Der_Missionar t1_ixcnejm wrote

Reply to comment by SocksOnHands in TIL the Passemant astronomical clock in Versailles has shown the correct date, time, moon phase, planetary alignment, etc (accounting for leap years ) from 1750 and can display through 9999. by kitkatbloo

>Was it that it was set in 1750 and is still correct today, or had the clock ever needed to be adjusted to correct the time?

This is exactly what I'm referring to... NOWHERE in the articles I've seen mention how accurate the clock is. I don't know a single mechanical clock that's ever been made that doesn't need to be adjusted from time to time. The post title leaves you thinking, this clock is accurate till 9999... and it's never been adjusted... that's not what this says at all.

Clocks of the day (1700's) often kept time to 1 second per day, and new mechanisms were coming out that could keep time to 1 second per month... John Harrison proposed a time-piece that could keep time to an astonishing 1 second per 100 days... His design, however, was never finished... until someone tried it out in 2009, and finished in 2012... proving you COULD keep time with his design, in a purely mechanical clock, (without crystals, like many of today's clocks), to within 1 second per 100 days.

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SocksOnHands t1_ixcy063 wrote

Ok, sorry. My confusion was from the title saying that it "shown the correct date, time... from 1750". Any clock can be "correct" if it is constantly being corrected by someone.

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DrugChemistry t1_ixcqlgh wrote

Why does it lack crystals? My understanding is that the jewels in a clock/watch movement are placed in places where things spin. The jewels lower the friction between pieces and are hard so they don’t need frequent replacement.

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