As someone pointed out, it is dependent on where you are, as well as a number of other factors.
I've got a nice chunk of concrete tied to bedrock about 10' below the surface with a thermal variation that is below the threshold of the thermometer i have there. Since I need to put something else on the concrete block (seismograph) I thought it might be interesting to toss a frequency std on it a well. Yet another project...:) On Jul 13, 2012, at 20:25, Neville Michie <namic...@gmail.com> wrote: > > You have to go deep into the ground to get stability. > At 15 metres deep there is a lovely pure sine wave of about 0.3C P-P. > I measured it on the roof of a cave, its period one year. > My design for the bolt is to put it in a 1/4 inch thick aluminium box which > is held at a constant temperature by a fan. Switching control is good enough > as the > thermal diffusivity of 1/4 inch aluminium will attenuate any spectral > components shorter than > a minute. The aluminium box is so conductive that the box is isothermal, so > once the bolt > has established its internal temperature gradients, nothing changes. > cheers, > Neville Michie > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
