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On 10/21/2013 3:49 PM, Bernard Cleyet wrote [in small part]:
some better clocks use silica pendula in addition to reduced thermal sensitivity./snip/
bc maths declined, so won't even try a trial solution.
I recall that a fused silica rod may be purchased at inconsiderable cost from a US source.
These shiny glass surfaces have a quasi-hygroscopic property which has apparently defeated some precise measurements of small weights
: still, the wooden pendulum has a thermal coefficient which may be quite low, but is also rather hygroscopic.
I recall some suggestions that miniature ball races cleaned of all lubricant can serve as relatively low-loss pivots, eliminating the flexure's variation in effective pendular length with amplitude and mass.
Brian Whatcott Altus OK
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