Brooke Clarke wrote: > Hi Mike: > > Back in the 1800s clock makers found ways to temperature compensate the > pendulum such as putting a Mercury thermometer at the bottom, using metals > with > dissimilar expansion coefficients (Harrison used steel and bronze (no zinc > then)) or materials with almost zero COE like Invar. > > The Dent clock at Greenwich in 1885 had an arenoid type compensator to remove > barometric pressure effects, later clocks were run in vacuum. > > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.precisionclock.com > Brooke
Invar and super Invar sound OK except that they are notoriously unstable with the dimensions changing slowly over time even at constant temperature. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
