[time-nuts] Hello

[Tom Van Baak]

> The Shortt pendulum was of great interest - what could 70 years
> of relentlessly advancing technology have to improve on it?
> That is a top priority, behind consulting commitments, financial
> management, home maintenance, building computers and looking for
> business. Which is to say, I've bought things but haven't had any
> time to do anything with them, like the Invar rod.

I would be interested if others of you time-nuts are also
involved with pendulum clocks. At the surface it might
seem odd that with today's technology that anyone would
want to spend time with pendulum clocks. But there are
several hundred guys around the world who are spending
a great deal of time working on modern pendulum clocks.

The history, science, and technology of these things is
far, far deeper than you might think. Here I can make a
plug for Jim's website:
http://www.clockvault.com/heritage/index.htm
and also have a look at Bill's amazing creations:
http://www.precisionclocks.com/

I really like my cesium clocks, but you've got to admit
these old (Riefler and Shortt) and new (Q1 and Q2)
are much better eye candy and old HP or FTS clock.

> Many years later, I've been able to buy much more than I've been
> able to do. My dear and patient wife wants to know when she will
> be able to move about the basement again. We approach 70 now, so
> it's not like we'll be searching for alternative partners.
> 
> But I digress. My research has shown that a free pendulum would be
> doing well to approach 10E-8 in accuracy. The folks on this list
> are going for 10E-12.

Right, the best ADEV you can do with a pendulum clock
is about 5e-9 for a tau on the order of days. I should send
you the plots.

> I no longer think that I will assemble a vacuum pump, tube, zero-loss
> pivot, and electrostatic detection and excitation mechanisms in my
> lifetime. Especially since I live 100 meters from a low-speed freight
> railroad track. Pity, really. Too soon old, too late smart.

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).

/tvb
http://www.LeapSecond.com