> As far as I can tell the Russian Fedchenko observatory clock was the > ultimate. > About 2 milliseconds per day.
Yes, word on the street is that the Russian Fedchenko did even better than Western pendulum clocks by Shortt, Riefler, and Leroy. Possibly because it well-addressed the issue of circular error. Perhaps because rusky fiscal-irrelevant invar was much better than capitalist make-a-profit invar. If you're interested I have, somewhere, nice long-term phase plots of a Fedchenko clock. I also know a couple of people that own them, although I'm not sure how many surviving Fedchenko's are in operational condition. I don't know how many time nuts are interested in this but you need to realize that the first hint that the Earth itself was an unstable timekeeper came, not from quartz or atomic oscillators, but from these astronomical pendulum clocks. When two or three Shortt's or Fedchenko's agreed better than earth-based stellar observations the only rational conclusion was that mechanical clocks were more stable than the earth itself. This had far-reaching philosophical and metrological implications. And it is much related to the origin of the leap second, in case you wondered why I'm interested in it. See also: http://www.leapsecond.com/museum/earth/ /tvb http://www.LeapSecond.com _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts