Re: Fused quartz pendulum  temperature coef
Harvey Moseley
Hi All, Just a brief comment on temperature compensation of the pendulum. Since we know accurately the coefficients of expansion of the suspension, pendulum rod, and pendulum bob, you can determine accurately where along the length of the bob to provide first order compensation for the expansion or contraction of the materials in the pendulum system. If we provide accurate first order compensation, the variation of the pendulum should be parabolic in temperature around the design temp. The breadth of the parabola should be proportional to the second order changes, which for most materials, are proportional to their coefficient of expansion. Bottom line, we can design the system to have no first order changes in period at the reference temp. The breath of the residual quadratic variation will be determined by the coefficients of the suspension and bob. Keep them all small, and the residual will be small. This ignores any thermal effects from the air, which I think is of higher order, and thus of lower importance. Hope this is helpful to those thinking about these system. Best Regards, Harvey
On Sat, Apr 11, 2020 at 10:25 AM James Meaton via groups.io <soundhutch=blueyonder.co.uk@groups.io> wrote:

