There is at least one in DC, at the Smithsonian iirc. RPI, where I went to college, had one in the 3 story stairwell in the library. Don't know if it is still there.
I remember one someplace in London too. Someone mentioned temperature compensation. What would you need to compensate for? Temp change in the wire wouldn't effect the rotation as far as I can tell. Swing length might be different based on temp of the wire I guess, but with a long pendulum, I think the magnet is going to way overcome that issue. The one @ RPI had issues due to air movement in the shaft, but that's a different problem. I suppose the right method is to use a GPS disciplined oscillator and the appropriate divider to drive the magnet under the floor. :) To cut down in draft induced drift and jitter, you'd have to put the whole thing in a vacuum though! On Wed, Jul 21, 2010 at 10:13 PM, Richard (Rick) Karlquist <rich...@karlquist.com> wrote: > > > Hal Murray wrote: > >> Several years ago, I found a web site for a commercial place that made >> them for museums. (I forget why I was looking for that sort of stuff.) You >> might find interesting stuff/ideas via google but I didn't find a similar >> site with a bit of searching. >> > > The Museum of Science and Industry in Chicago had one when I lived > there in the 1960's. > > Rick N6RK > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.