Over 50 years ago the French scientist Allais observed:
“During the total eclipses of the sun on June 30, 1954, and October 22, 1959, quite analogous deviations of the plane of oscillation of the paraconical pendulum were observed…” – Maurice Allais, 1988 Nobel autobiographical lecture.
And back in 01999 NASA reproduced the experiment and the effect during the total eclipse that year at multiple Foucault pendulums. I have been following this since learning of Allais’ original claim when I started working with Danny Hillis on the design of the 10,000 Year Clock. It seemed to me it might lend itself to a way for the Clock to mechanically record eclipses as they occur through the centuries and millennia. (One of my favorite Long Nowish publications is the 5 millennia Canon of Solar Eclipses [NASA page]) Unfortunately I cannot find much follow up to the 01999 experiment (any links appreciated). It would be very fun to build a device that capitalized on the effect as part of a 10,000 Clock.