[time-nuts] Hello

Tom Van Baak tvb at LeapSecond.com
Tue Mar 27 23:26:17 EDT 2007


>> Yes, others working with pendulums have also discovered that they end
>> up making crude thermometers, barometers, or seismometers instead of a
>> good clock. Still, not a reason to give up. But you know you have a
>> world-class pendulum clock when, after having solved every other
>> perturbation, you can see the effects of lunar tides in your data (as
>> your good pendulum clock demonstrates it is also a fair gravimeter). 
> 
> That seems like a neat threshold.  Are current pendulum clocks good enough to 
> notice tides?  When was the first published paper?  If not, how close?

Yes, it is a neat benchmark. Not a few modern clock makers
have tried to reproduce or improve on the old masters. It turns
out a pendulum clock needs to be accurate (stable) to 1e-7 or
1e-8 for tau from an hour to a day in order for it to "detect"
tides. See this article I wrote a while back on the subject:

    Lunar/Solar Tides and Pendulum Clocks (part 1)
    http://www.leapsecond.com/hsn2006/ch1.htm

Not sure what you mean by "current" pendulum clocks. I think
modern commercial pendulum clocks are nowhere as accurate
as the state-of-the-art pendulum clocks of the 1920's. Quartz
clocks in the 30's and atomic clocks in the 50's put an end to
the market for ultra precise pendulum clocks.

/tvb




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