On Thursday, November 17, 2011 10:58:38 PM Kent A. Reed did opine: > Gentle persons: > > Gene Heskett asked me if there is a website describing the > Shortt-Synchronome clock I mentioned. One could start at > http://en.wikipedia.org/wiki/Shortt-Synchronome_clock which includes a > photograph of the one at NIST, No. 32 out of perhaps twice that many > sold to others.
Amazing for its day, and still damned impressive. Obviously the output of a genius mind. Thanks Kent. The only detail the wiki didn't cover was the method of detecting the position of the master pendulum. In 1920 we had no vacuum phototubes (that I am aware of that is) which could have optically measured the position of the pendulum without acting as a large friction loss. Their statement that it had a 'Q' of 110,000 is close to a cheap quartz crystal's performance today, one that is not vacuum sealed but is running in the usual ambient pressure dry nitrogen atmosphere. > The reasons I fell in love with it include: > > 1) it consists of two pendulums, one running in a commonplace industrial > clock---the Synchronome time transmitter---and one running in a > vacuum---the Shortt free pendulum---cross-coupled electrically, that was > the most accurate pendulum clock in the world. It that was surpassed as > a time keeper only when crystal oscillators were put to the task. As a > physicist, I admired this ingenious coupled oscillator system and the > two men who invented it. > > 2) the clock is a precise time keeper but it is very imprecisely made. > Most of the Synchronome parts could be hacked out of pieces of flat and > round stock using saws, files, and drill bits (so why CNC? Because I say > so, that's why!). The principal difficulty with the Shortt free pendulum > is its vacuum encasement, and more than one amateur has simply ignored > that bit and lived with the loss of precision. Anyone looking at this > clock would think "Heck, I could do that." Compare it to the Riefler > observatory clock that hangs near the Shortt-Synchronome clock at NIST. > One look behind the Riefler dial or at the Riefler patent drawings would > convince one that this is a project for the masters (see, for example, > http://www.brown.edu/Departments/Physics/Ladd/instruments/clemens.html). Agreed, and woefully short of details, like is that a hand pumped vacuum pump in front it its cabinet/tank? > 3) Frank Hope-Jones, the inventor and manufacturer of the Synchronome > clock and first the boss and then collaborator of William Hamilton > Shortt, the inventor of the cross-coupled free pendulum, explicitly > supported amateurs desiring to make their own copies of his clocks, even > providing kits of rough parts long ago. He openly published on all > aspects of his clocks. (He was also a shameless self-promoter as you'll > see in all his publications, but what the heck, nobody's perfect.) No > trade secrets and no patent trolls to deal with. The 500 or so members > of the Yahoo Synchronome Group now have wider interests than just the > Synchronome but many members own genuine Synchronome time transmitters > or have made their own. > > Regards, > Kent Thanks Kent. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> In 1880 the French captured Detroit but gave it back ... they couldn't get parts. ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
