Hi Carl: That's interesting. After reading Accurate Clock Pendulums and a number of other books then researching patents I found:
3036465 Gravity Meter, Robert H. Dicke, May 29, 1962, 73/382R ; 73/514.29 >= 20 cps, Q >1,000,000 optical pick up and electrostatic drive, mostly fused quartz parts. He also invented the lock-in-amplifier and Dicke radiometer. http://www.prc68.com/I/Pendulums.shtml It's almost all quartz, but now I see why they are not more popular. Have Fun, Brooke Clarke http://www.prc68.com/P/Prod.html Products I make and sell http://www.prc68.com/Alpha.shtml All my web pages listed based on html name http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam Carl Dreher wrote: > Hi, > This is my first input to the list. >>From what I've read, the jump in pendulum clocks is due to a spontaneous > change in the rod length. This has actually been measured, and is > accredited to crystal lattice slippage of the material. This has been > found in metal and recently, crystal rod pendulum. It is significant in > the latter because experimenters went to crystal rods for their > temperance invariance, only to find the unpredictable spontaneous length > change. > > Carl Dreher > ============== > In : Accurate Clock Pendulums by Robert Matthys (2004) Oxford > University Press ISBN 0198529716, Pp264 > In Chapter 8 , "The Allen variance and the rms time error", on page 38 > he writes: > Figure 8.1 shows another characteristic of pendulum clocks - the > clock will run relatively > smoothly at one rate , and then after 3 - 6 months it will suddenly > jump to a new rate > as shown if Fig 8.1. > > He goes on to say that this is part of a random walk process. > > I hope that is of some help. > Neville MIchie > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
