Re: Fused quartz pendulum - temperature coef


Neil, yes Matthys says in his book (pag 3) that it's better ( and easier) to hang a bob from the bottom edge.  Where di you get the description of his experimets though?
What I was saying is that while designing the new bob for my pendulum I realized that the Synchronome original one seems to have been designed for exact compensation, within my ability of determining the gray cast iron and the invar TC.

Two reasons for pointing this out: historical on the Synchronome genesis, it would be nice to know if my guess is right, James Meaton who worked for them might know.

Second, to figure out if it's worth doing so in general.  The only way to understand it would be to measure the effects of putting efforts at this kind of temperature compensation, it's not obvious to me that exact temp comp of the rod and bob thermal expansion leads to a proportional reduction in temperature sensitivity of the period at the level of precision we are interested in. A couple of months ago while I was modifying the bob I exploited the occasion to install 15W of LED strip lights inside the case which, with the inside 4 thermometers, should provide a reasonable chance of controlling the clock temperature boundary conditions. My intuition tells me that the ability to modulate the temperature would be more useful, and easier to implement, than to heavily insulate the case both for sensitivity and to separate time constants. No time to use the system yet though.


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