[time-nuts] Re: in-ground clock room

[Poul-Henning Kamp]

--------
Tom Van Baak writes:

>For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So 
>that's vastly smaller than digging a basement, but much larger than 
>drilling a 8 inch round pipe. Digging down gives some natural isolation 
>and temperature regulation. A couple tons of concrete gives high 
>stability vertical walls for the pendulum clocks.

I researched this extensively before we built a house 5 years ago.

Look at the plot on page 37 in this paper:

	https://www.researchgate.net/publication/279526204_Temperatur_og_temperaturgradienter_ved_og_under_jordoverfladen_i_relation_til_lithologi

It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.

I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.

In the end I concluded that I could do better in the comfort of my lab.

You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.