[time-nuts] gravity controlled pendulumn clock?

Bill Hawkins bill at iaxs.net
Mon Dec 12 22:17:07 EST 2011

Let's see, arguably the most accurate pendulum clock was the Shortt clock.
It was good to 200 microseconds/day, or about 2 E-9, where you could see
the effect of the moon and the sun, just.

Suppose I have one of those beauties in my basement, with the requisite
apparatus to compare it to a Caesium clock disciplined by GPS. Suppose
my wife drives her 3000 pound car out of the garage, about 20 feet away.
What will be the affect of that local change in mass?

Could I discipline a Shortt clock to GPS by using a PLL that slid a one
ton mass along the basement floor near the free pendulum? Sliding the one
ton mass is left as an exercise for the reader, as is installing it in the

Yours in search of more perfect knowledge outside my field,

Bill Hawkins

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