[time-nuts] Low power timekeeping

[Hal Murray]

albertson.chris at gmail.com said:
> I figure the thermal mass of many tons of concrete and soil must be, well a
> lot.

The concept you want is skin depth.  It's not the thermal mass, it's the 
ratio of mass to conductivity.

I haven't found a good web page.  This one has a table on page 27.  It 
depends upon the material: ballpark is 1 to 4 meters.
  Temperature as a function of depth and time Paul Evans & Christine Wittich
  http://topex.ucsd.edu/geodynamics/HW3_2011_presentations/C_wine_cellar.pdf

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