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

[djl]

I think you can use precast concrete such as a septic tank or rings. My 
measurements made a LONG time ago in NM indicate that a mere 18 inches 
depth leads to less than one degree (God's units as revealed by the 
French) over the period of a year. Bring wiring in via a trench at the 
surface level of the top of the vault. Ideally, the cover should be 
insulation to near surface, then soil. That's the one sticky point 
because as you will know, thermal vortices will be set up in the vault 
air. very small slow fans may control?  The flow can be modeled,  I 
think.
Don

On 2021-09-08 19:54, Tom Van Baak wrote:
> I am considering a below ground "clock room" away from the house. This
> will be for some low-drift quartz oscillators and also a couple of
> precision pendulum clocks. The goal is long-term, unattended, and very
> undisturbed operation.
> 
> 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.
> 
> If any of you have personal or professional experience with the design
> or construction of this sort of thing, especially experience with
> precast (utility) vaults or poured concrete, please let me know.
> 
> In case this gets too off-topic for time-nuts, off-list email to me is
> fine (tvb at leapsecond.com).
> 
> Thanks,
> /tvb
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------------
The whole world is a straight man.
----------------------
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304