Oh Dear! What have I started? ;-)
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bill Hawkins Sent: 09 August 2010 21:36 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Regulating a pendulum clock Ahhh, this is more like it! Large gears and thick ropes moving heavy weights up and down. :) Of course, you wouldn't want anything digital doing this. Just a large pendulum clock driving a maze of gears that calculate solar and lunar positions. Bill Hawkins -----Original Message----- From: J. L. Trantham, M. D. Sent: Monday, August 09, 2010 3:10 PM Personally, I would get out of the way. : ) Joe -----Original Message----- From: Ian Sheffield Sent: Monday, August 09, 2010 1:17 PM What happens when the rope breaks? -----Original Message----- From: J. Forster Sent: 09 August 2010 19:10 You could put a large mass of concrete or somehing above the clock and crank it up and down, to balance out the computed gravity changes. :) -John > Unfortunately Gravity is not constant. Pendulum clocks show cyclic errors > due to the influences of the Moon's and Sun's Gravitational fields. I > forget the amounts but it is in the region of parts in 10 to the 7, which > is easily measurable. > > This limits the compensations one can put into a pendulum clock. > > > -----Original Message----- > From: mike cook > Sent: 09 August 2010 18:21 > > On 09/08/2010 18:46, Bob Holmstrom has written: >> >> Food for thought. >> >> I find it interesting that no one has suggested alternatives to >> improving the performance of a pendulum clock other than controlling >> it with a higher performance clock. If the goal is a better clock why >> not attempt to understand the source of the errors and work on methods >> to control or compensate for them? Teddy Hall has been taken to task >> for using a quartz controlled oscillator to measure the amplitude of a >> pendulum in the control loop of his Littlemore clock. >> >> Tom Van Baak has developed techniques for analyzing the performance >> and hence potential error sources of pendulum clocks - perhaps he will >> share some of his work here. >> >> Horological history is full of many attempts at solutions to the >> problem, but it would seem that the creativity of this group might >> generate some new ideas that are more in the spirit of better >> timekeeping than attaching the pendulum to a better oscillator. >> >> How about a wireless controlled device attached to the pendulum that >> changes its position based on error sensor readings, not time errors, >> but instead, temperature, barometric pressure, gravity, etc. that >> would maintain a more constant pendulum period? > > Yup. We have temperature and pressure ICs available , I think that > gravity is pretty constant if the clock isn't being moved about. > Humididty might also need logging aswell. So it should be easy enough to > predict the pendulums response to changes given a reasonable time of > observation. > That said, clocks have always been adjusted against better > references.. IIRC Harrison (and probably others) was using star transits > to regulate his long case clocks. >> >> Bob Holmström >> Editor >> Horological Science Newsletter >> www.hsn161.com _______________________________________________ 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.
