[time-nuts] Non electrical time-nuttery

[Hal Murray]

james.p.lux at jpl.nasa.gov said:
> A Shortt pendulum (whatever that is, I'll have to go look it up) is
> 1E-7.  A friend of mine was trying to build a 1ppm pendulum clock 15
> years ago, with temperature compensated weights, etc.

Google will keep you busy for a long time.

They were the best clocks of their day, a giant step ahead of any others.
  http://www.clockvault.com/heritage/index.htm
 This Shortt Clock, serial number 6, was also purchased by Admiral Fountaine 
for his private observatory in 1924 and replaced his Riefler clock. The clock 
was installed in the Admiral's clockvault and its rate was carefully compared 
to astronomical observations. Admiral Fountaine's observations were so 
precise that they indicated small variations in the earth's rotation. 
Fountaine insisted that these irregularities were due to the earth not the 
clock. The Greenwich Observatory confirmed these nutations in 1927.

But they weren't pure mechanical.  They had an electric switch that got the 
signal to the outside world and I think they were driven by an electro magnet.

There is nice discussion of Shortt clocks in Tuxedo Park.  Loomis had 3 of 
them.


> So, can one build a 1E-8 performance clock, without electricity?

Seems pretty ambitious.  A reasonable goal would be measuring tides.
  http://www.leapsecond.com/hsn2006/



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