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

[Bob kb8tq]

Hi

You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….  

How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood.  Part of this is the geology,
part is how the builder graded things to  put in the subdivision. 

While that *sounds* ideal, the shale is tilted due to some thing running into
something else a while ago. The net result is ground water running here 
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for 
temperature stability. 

Yes, it’s all about some *very* local aspects of your geology.  With some 
care, I could move a few miles in one direction or another and be in a *very* 
different situation. (again thanks to just how this ran into that ….).  

Since temperature stability is only part of the design and mechanical 
stability is the other. This location might work ok for half of the design 
goals …. Granite likely would do better than fractured shale though ...

Bob

> On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> 
> --------
> 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.
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