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Re: [Phys-L] Mesmerizing

On 2013, Sep 15, , at 17:13, brian whatcott <> wrote:

It was found that observatory pendulum mounts were a significant source of error. The remedy for this mount compliance was the use of a short stiff beam mount for two pendula in phase opposition - which reduced or eliminated the effect. Engineers are familiar with the virtues of the Boxer engine configuration, like the original VW bug engines which bled up into the Porsche,as well as the Lycoming and Continental air-cooled reciprocating engines, for a somewhat similar reason. It was a short hop from the dual pendulum to the electrically maintained vibrating fork, which led to the quartz tuning fork configuration, before timing frequencies went higher with simpler quartz slab configurations. All in just a lifetime....

Brian Whatcott Altus OK

There's a Sci. Am. article in the Amateur Scientist describing the double pendulum to eliminate support motion. (August 1960)

Moreover, the "amateurs" also added a rotating arm to cancel out of plane motion.

bc thinks the cylinder preceded the slab and fork. (Marrison)