I suppose one could argue that even a manually disciplined clock (e.g., analog AA wall clock in the kitchen) is ultimately computer regulated when flicking the hands while glancing at a cell phone.
The 10,000-year clock is disciplined by the Sun, though for some functions this is relative to its equation of time cam machined to deliver the result of computations performed by JPL: * http://blog.longnow.org/02007/06/04/solar-synchronizer/ * http://blog.longnow.org/02018/12/05/the-equation-of-time-cam-keeping-good-time-for-10000-years/ Rob -- On 2/8/19 6:29 AM, Tom Van Baak wrote: > (steering the topic back to steps, smears, and leap seconds) > > Tony, Rob, > > It's not surprising if the Corpus Clock is disciplined against MSF. This > trick is used more often than you think. John C Taylor presented at the > Caltech "Time for Everyone" symposium in 2013: > > http://saving-time.org/timeforeveryone/speakers/dr-john-c-taylor > http://saving-time.org/timeforeveryone/program/ > > While there he revealed another of his inventions, the "intelligent > pendulum", which you can see in the top third of this image from his web site: > > http://www.johnctaylor.com/wp-content/uploads/2014/03/montage-myvision-science.jpg > > A more detailed set of photos and description of the prototype is found here: > > http://www.marbleproductdesign.co.uk/projects/intelligent-pendulum.php > > It's a battery operated device that functions both as a cosmetically > appropriate pendulum bob (of sufficient mass) and an accurate quartz clock > (of superior accuracy). The trick is to use an embedded accelerometer and > microcontroller to detect and measure the periodic swinging motion and > compute the mean period of the pendulum using the quartz oscillator as a time > reference. Then, if the pendulum rate is found to be inaccurate, that is, if > the pendulum is drifting in time, the device activates a geared-down stepper > motor to climb up or down the pendulum rod some fraction of a mm in order to > correct the rate. No different than NTP, really. > > For a standard seconds pendulum (length ~1 meter, period ~2 seconds) changing > the location of the mass by 1 mm results in a 500 ppm change in rate, > equivalent to ~40 seconds/day. To make a one second per day change one only > needs to move the bob by 20 microns. Don't laugh. This is done. Precision > pendulum clocks are a world where microns and microseconds matter a lot. And > leap seconds are a pain for them too. > > There's a wonderful BBC video showing how Big Ben is adjusted for leap > seconds: > > "Leap second: Slowing down Big Ben" [1] > http://news.bbc.co.uk/2/hi/science/nature/7792436.stm > > In this case they do not literally move the massive weight up or down, but > instead, by adding tiny weights (usually penny coins) they change the > effective center of gravity of the bob, which is all that matters. This is an > unexpected application of the saying that "time is money". > > /tvb > > [1] If someone (UK only?) can capture this short video as mp4 I'd appreciate > it. > > _______________________________________________ > LEAPSECS mailing list > [email protected] > https://pairlist6.pair.net/mailman/listinfo/leapsecs
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