[time-nuts] Improving the stability of crystal oscillators

[John Miles]

> The required depth depends on the soil diffusivity and the temperature
> stability required.
> It is instructive to install thermometers at depth intervals of a foot
> or so and record the temperature fluctuations experienced by each
> thermometer.
> This was first done around 1860 by Forbes.
> I repeated the experiment in 1966.

There was an interesting bit in the last Agilent Measurement Journal about a
product that uses an ordinary communications-grade fiber as a thermometer.