[time-nuts] Re: in-ground clock room
Gilles Clement
clemgill at gmail.com
Sat Sep 11 09:02:19 UTC 2021
Magnetic levitation, dampening external vibrations ?
GC
> Le 10 sept. 2021 à 23:03, Jerome Blaha <jblaha at polariswireless.com> a écrit :
>
> Would the use of a partial vacuum in a sealed chamber or even the septic tank to reach a somewhat steady-state temperature be out of the question, as only radiation would dominate the temperature?
>
> Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might be attainable with a double or triple stacked pettier cooler (reversible in voltage if your outdoor temps get below 0C) with very small tubing with coolant and two tiny DC powered pumps for redundancy with check valves to a small radiator inside the crypt water/ice bath with an RTD temperature sensor. Throw in an above-ground solar and battery backup, and the solid-state refrigeration unit could be fully self-contained and located far enough from the time crypt to not influence gravity, magnetism, quantum physics, etc.
>
> -Jerome Blaha Jr
>
>
>
> -----Original Message-----
> From: time-nuts-request at lists.febo.com [mailto:time-nuts-request at lists.febo.com]
> Sent: Friday, September 10, 2021 12:30 AM
> To: time-nuts at lists.febo.com
> Subject: time-nuts Digest, Vol 209, Issue 7
>
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> Today's Topics:
>
> 1. Re: in-ground clock room (B Riches)
> 2. Re: in-ground clock room (Dana Whitlow)
> 3. Re: in-ground clock room (Andy Gardner, ZL3AG)
> 4. Re: in-ground clock room (Dana Whitlow)
> 5. Re: in-ground clock room (Bob kb8tq)
> 6. Re: in-ground clock room (Brent)
> 7. Re: in-ground clock room (Joseph Gwinn)
> 8. Re: in-ground clock room (Steve Allen)
> 9. Re: in-ground clock room (Scott McGrath)
> 10. Re: in-ground clock room (Dana Whitlow)
> 11. Re: in-ground clock room (Gilles Clement)
> 12. Re: in-ground clock room (John Marvin)
> 13. Re: [time nuts] Re: in-ground clock room (Bill Beam)
> 14. Re: in-ground clock room (Lux, Jim)
> 15. Re: in-ground clock room (Graham / KE9H)
> 16. Re: in-ground clock room (Ben Bradley)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 9 Sep 2021 11:17:02 +0000 (UTC)
> From: B Riches <bill.riches at verizon.net>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>, Tom Van Baak <tvb at leapsecond.com>
> Message-ID: <376021411.3362644.1631186222747 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> How about using a round septic tank. Mine is about 5 feet wide and 6 feet deep Large hole in the top - put ladder for entry.
> 73,
> Bill, WA2DVUCape May, NJ
> On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <wbeam at gci.net> wrote:
>
>> On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
>>
>> On Wed, 8 Sep 2021 18:54:03 -0700, 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
>
>> Tom,
>
>> How long do you expect your proposed voult to go undisturbed?
>> I have several pendulum clocks. They are disturbed every couple of months
>> by earth quakes. By disturbed, I mean pendulum banging against the case walls....
>> Any ground motion that can be felt will upset the clocks. Often the clocks will
>> signal an earth quake that is not felt.
>
>> Good luck.
>
> I spent a few years as a geotechnic/soils engineer and learned as others have pointed out
> that a thermal wave of period one year and wave length of several meters propagates
> downward thru the soil. Peak amplitude of a few degrees can be expected near the surface.
>
> Consider building an "oven" with the clock vault freely floating in a water-ice mixture. This will
> provide constant temperature (0C) and limited mechanical isolation from earth quakes.
>
> But of course this will be expensive to operate.
>
> As you know 'good' clocks require a lot of energy and generate a lot of entropy.
>
> Protecting the quartz oscillators is much easier than protecting the pendulum clocks.
>
>
>
>
> Bill Beam
> NL7F
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 2
> Date: Thu, 9 Sep 2021 07:09:33 -0500
> From: Dana Whitlow <k8yumdoober at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CADHrwpfdjccbGnwncxsSSnGipix9NfcKXD5f3HJjS3eivAqJ6w at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> It seems to me that in order to derive much thermal stabilization, the *top*
> of the space would need to be several feet underground (depending on
> geographic location). And I think that the means for human access would
> likely "spoil the broth" unless fairly extreme measures were taken.
>
> Wouldn't it be sufficient to use a space whose thermal coupling were weak
> enough to make the time constant a few days (instead of months)? Then,
> ordinary inexpensive means like GPS-locked Rb standards with suitable
> (longish) time constants should clean up "GPS noise", yet enable the loop
> to take care of low rate temperature variations in the protected space due
> to outside temperature changes.
>
> Remember, perfection in clocks is expensive- according to recent things I've
> read about entropy of timekeeping, a perfect clock would require infinite
> power,
> and that alone would blow away all one's efforts at temperature control.
>
> Dana
>
>
> On Thu, Sep 9, 2021 at 6:19 AM B Riches via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
>> How about using a round septic tank. Mine is about 5 feet wide and 6
>> feet deep Large hole in the top - put ladder for entry.
>> 73,
>> Bill, WA2DVUCape May, NJ
>> On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <
>> wbeam at gci.net> wrote:
>>
>>> On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote:
>>>
>>> On Wed, 8 Sep 2021 18:54:03 -0700, 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
>>
>>> Tom,
>>
>>> How long do you expect your proposed voult to go undisturbed?
>>> I have several pendulum clocks. They are disturbed every couple of months
>>> by earth quakes. By disturbed, I mean pendulum banging against the case
>> walls....
>>> Any ground motion that can be felt will upset the clocks. Often the
>> clocks will
>>> signal an earth quake that is not felt.
>>
>>> Good luck.
>>
>> I spent a few years as a geotechnic/soils engineer and learned as others
>> have pointed out
>> that a thermal wave of period one year and wave length of several meters
>> propagates
>> downward thru the soil. Peak amplitude of a few degrees can be expected
>> near the surface.
>>
>> Consider building an "oven" with the clock vault freely floating in a
>> water-ice mixture. This will
>> provide constant temperature (0C) and limited mechanical isolation from
>> earth quakes.
>>
>> But of course this will be expensive to operate.
>>
>> As you know 'good' clocks require a lot of energy and generate a lot of
>> entropy.
>>
>> Protecting the quartz oscillators is much easier than protecting the
>> pendulum clocks.
>>
>>
>>
>>
>> Bill Beam
>> NL7F
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 3
> Date: Fri, 10 Sep 2021 00:29:15 +1200
> From: "Andy Gardner, ZL3AG" <zl3ag at radioengineering.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: time-nuts at lists.febo.com
> Message-ID:
> <0615ccea-ea7e-a4e3-7c19-8767c37d28e3 at radioengineering.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
>
>
> So the 2 things you're after are thermal insulation and vibration insulation?
>
> Digging can be expensive, and you have to worry about water table in many locations.
>
> How about the thickest concrete water tank you can find, plonk it in a nice location, spray layers of polyurethane foam over the top and sides for thermal insulation, then build a wind shield ("shed") around it. The shed could be an old coolstore, adding more insulation.
>
> Concrete water tanks are out of fashion these days due to plastics, so if you shop around you can find a cheap used one, and then it's just the trucking/crane charges.
>
>
>
> ------------------------------
>
> Message: 4
> Date: Thu, 9 Sep 2021 07:38:30 -0500
> From: Dana Whitlow <k8yumdoober at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CADHrwpdUZSteVrKK_PKfbsCYcJX311TAj7=TBQ7NaYofOpum_w at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Tom,
>
> Andy brings up good points, especially about water leaks.
> Are you familiar with "Whitlow's 5th law" (which can be summarized
> as "everything leaks")?
>
> Dana Whitlow
>
>
> On Thu, Sep 9, 2021 at 7:29 AM Andy Gardner, ZL3AG via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
>>
>>
>> So the 2 things you're after are thermal insulation and vibration
>> insulation?
>>
>> Digging can be expensive, and you have to worry about water table in many
>> locations.
>>
>> How about the thickest concrete water tank you can find, plonk it in a
>> nice location, spray layers of polyurethane foam over the top and sides for
>> thermal insulation, then build a wind shield ("shed") around it. The shed
>> could be an old coolstore, adding more insulation.
>>
>> Concrete water tanks are out of fashion these days due to plastics, so if
>> you shop around you can find a cheap used one, and then it's just the
>> trucking/crane charges.
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
>
> ------------------------------
>
> Message: 5
> Date: Thu, 9 Sep 2021 09:04:04 -0400
> From: Bob kb8tq <kb8tq at n1k.org>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Cc: Tom Van Baak <tvb at LeapSecond.com>
> Message-ID: <E624E63E-7BCD-49E8-9AF5-FF9C7C32E02B at n1k.org>
> Content-Type: text/plain; charset=utf-8
>
> 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://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~
>>
>> 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.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 6
> Date: Thu, 9 Sep 2021 10:12:06 -0400
> From: Brent <brent.evers at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CAP6i9Mni5LDGDaanNB5QP=SHtYErLQURBknu7iVo6CHaxaSPdA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Seismic vaults are built similar to your requirements. I suggest looking
> up the Earthscope program - there should be info out on the web as to how
> their vaults were designed, but in a nutshell, dig a hole, put some gravel
> in the bottom, place a large culvert on end in the hole, pour a few inches
> of concrete in the culvert, put instrumentation in a pedestal inside, run
> power and comms, put a bilge pump and outflow pipe in it on the floor
> (below pedastal), and put a cap on the whole thing. Those were then
> re-buried, but that prevents easy access (although it probably improves
> temperature stability). A septic tank would be larger, but more effort, and
> may expose more surface area to the sun (temp variation).
>
> I've been in various seismic vaults and they can vary from very extravagant
> to downright crude.
>
>
>
>> On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>>
>> 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://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~
>>>
>>> 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.
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe
>> send an email to time-nuts-leave at lists.febo.com
>>> To unsubscribe, go to and follow the instructions there.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 7
> Date: Thu, 9 Sep 2021 12:02:44 -0400
> From: Joseph Gwinn <joegwinn at comcast.net>
> Subject: [time-nuts] Re: in-ground clock room
> To: time-nuts at lists.febo.com
> Message-ID: <20210909120244341063.4dfa1be6 at comcast.net>
> Content-Type: text/plain; charset=iso-8859-1
>
> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request at lists.febo.com
> wrote:
> Re: time-nuts Digest, Vol 209, Issue 6
>
>
>> ------------------------------
>>> Date: Wed, 8 Sep 2021 18:54:03 -0700
>> From: Tom Van Baak <tvb at LeapSecond.com>
>> Subject: [time-nuts] in-ground clock room
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at lists.febo.com>
>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf193274d6 at LeapSecond.com>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>> 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).
>
> As others have said, it may not be economically practical to build an
> underground clock room.
>
> Assuming that you have a basement of other suitable room in your
> house, I'd suggest an insulated box or room containing a big lump of
> iron riding on an inner-tube suspension of some kind. The big lump
> of iron can be a 500-pound truck engine head or block from a
> junkyard, steam cleaned (to remove oil) and painted (to keep the rust
> under control). Drill and tap holes as needed for mounting.
>
> This box/room plus block can be set up as a temperature-controlled
> oven with a few extra components, including a PID controller.
>
> Bolt a thick plywood floor to the top of the iron hunk, and attach
> the clocks to this floor.
>
> Joe Gwinn
>
> ------------------------------
>
> Message: 8
> Date: Thu, 9 Sep 2021 09:13:18 -0700
> From: Steve Allen <sla at ucolick.org>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID: <20210909161318.GA19164 at ucolick.org>
> Content-Type: text/plain; charset=utf-8
>
> On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ:
>> 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.
>
> How deep?
>
> Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment,
> facilities, and operations of Bureau International de l'Heure at
> Observatoire de Paris.
>
> The highest precision pendulum clocks, the ones which had mechanisms
> to correct for temperature and pressure (the "garde-temps") were kept
> 27 m below ground in caves and galleries which were part of the
> Paris catacombs.
>
> Various issues of Bulletin Horaire report discontinuities in the
> operation of those clocks due to distant earthquakes.
>
> --
> Steve Allen <sla at ucolick.org> WGS-84 (GPS)
> UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
> 1156 High Street Voice: +1 831 459 3046 Lng -122.06015
> Santa Cruz, CA 95064 https://url.emailprotection.link/?babImg0bEUxMHpPsxOmCp3Cn-KMvw54w86vJHHj3bTiz-n20wRlflI_23_p5IjE256VI1iFbNSdl2v6Rv0dqwQw~~ Hgt +250 m
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>
> ------------------------------
>
> Message: 9
> Date: Thu, 9 Sep 2021 12:28:00 -0400
> From: Scott McGrath <scmcgrath at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID: <0595152C-C512-45D9-8903-F2616D349B59 at gmail.com>
> Content-Type: text/plain; charset=utf-8
>
>
> Rather than custom casting a structure you might want to consider use of a precast concrete septic tank or transformer vault as cost will be much lower.
>
> You will also need to consider waterproofing the tank it already has a layer of waterproofing but a couple of additional layers will probably be necessary as well as ensuring proper drainage around it as it will need to be both above local water table and be able to drain off percolating rainwater.
>
> You will also need to control temperature and humidity
>
> On Sep 9, 2021, at 12:03 PM, Joseph Gwinn <joegwinn at comcast.net> wrote:
>
> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request at lists.febo.com
> wrote:
> Re: time-nuts Digest, Vol 209, Issue 6
>
>
>> ------------------------------
>>> Date: Wed, 8 Sep 2021 18:54:03 -0700
>> From: Tom Van Baak <tvb at LeapSecond.com>
>> Subject: [time-nuts] in-ground clock room
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at lists.febo.com>
>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf193274d6 at LeapSecond.com>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>> 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).
>
> As others have said, it may not be economically practical to build an
> underground clock room.
>
> Assuming that you have a basement of other suitable room in your
> house, I'd suggest an insulated box or room containing a big lump of
> iron riding on an inner-tube suspension of some kind. The big lump
> of iron can be a 500-pound truck engine head or block from a
> junkyard, steam cleaned (to remove oil) and painted (to keep the rust
> under control). Drill and tap holes as needed for mounting.
>
> This box/room plus block can be set up as a temperature-controlled
> oven with a few extra components, including a PID controller.
>
> Bolt a thick plywood floor to the top of the iron hunk, and attach
> the clocks to this floor.
>
> Joe Gwinn
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 10
> Date: Thu, 9 Sep 2021 11:35:30 -0500
> From: Dana Whitlow <k8yumdoober at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CADHrwpffWGTpaX+s02YfnEx704RP_5rWgxheFFjAb+ALf8iQEQ at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> One might also consider mounting smaller items inside the cylinders of the
> engine block,
> to get the most out of its thermal mass.
>
> Dana
>
>
>> On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn <joegwinn at comcast.net> wrote:
>>
>> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request at lists.febo.com
>> wrote:
>> Re: time-nuts Digest, Vol 209, Issue 6
>>
>>
>>> ------------------------------
>>>> Date: Wed, 8 Sep 2021 18:54:03 -0700
>>> From: Tom Van Baak <tvb at LeapSecond.com>
>>> Subject: [time-nuts] in-ground clock room
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at lists.febo.com>
>>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf193274d6 at LeapSecond.com>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>
>>> 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).
>>
>> As others have said, it may not be economically practical to build an
>> underground clock room.
>>
>> Assuming that you have a basement of other suitable room in your
>> house, I'd suggest an insulated box or room containing a big lump of
>> iron riding on an inner-tube suspension of some kind. The big lump
>> of iron can be a 500-pound truck engine head or block from a
>> junkyard, steam cleaned (to remove oil) and painted (to keep the rust
>> under control). Drill and tap holes as needed for mounting.
>>
>> This box/room plus block can be set up as a temperature-controlled
>> oven with a few extra components, including a PID controller.
>>
>> Bolt a thick plywood floor to the top of the iron hunk, and attach
>> the clocks to this floor.
>>
>> Joe Gwinn
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
>
> ------------------------------
>
> Message: 11
> Date: Thu, 9 Sep 2021 21:05:11 +0200
> From: Gilles Clement <clemgill at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID: <C3B65D1E-3EB2-42F0-8291-46EBA92DD8CA at gmail.com>
> Content-Type: text/plain; charset=utf-8
>
> With a slight cantilevered cavity at the base,
> instrumental as a *nut cracker… o:))
> * = time?
>
>> Le 9 sept. 2021 à 18:35, Dana Whitlow <k8yumdoober at gmail.com> a écrit :
>>
>> One might also consider mounting smaller items inside the cylinders of the
>> engine block,
>> to get the most out of its thermal mass.
>>
>> Dana
>>
>>
>>> On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn <joegwinn at comcast.net> wrote:
>>>
>>> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request at lists.febo.com
>>> wrote:
>>> Re: time-nuts Digest, Vol 209, Issue 6
>>>
>>>
>>>> ------------------------------
>>>>> Date: Wed, 8 Sep 2021 18:54:03 -0700
>>>> From: Tom Van Baak <tvb at LeapSecond.com>
>>>> Subject: [time-nuts] in-ground clock room
>>>> To: Discussion of precise time and frequency measurement
>>>> <time-nuts at lists.febo.com>
>>>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf193274d6 at LeapSecond.com>
>>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>>
>>>> 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).
>>>
>>> As others have said, it may not be economically practical to build an
>>> underground clock room.
>>>
>>> Assuming that you have a basement of other suitable room in your
>>> house, I'd suggest an insulated box or room containing a big lump of
>>> iron riding on an inner-tube suspension of some kind. The big lump
>>> of iron can be a 500-pound truck engine head or block from a
>>> junkyard, steam cleaned (to remove oil) and painted (to keep the rust
>>> under control). Drill and tap holes as needed for mounting.
>>>
>>> This box/room plus block can be set up as a temperature-controlled
>>> oven with a few extra components, including a PID controller.
>>>
>>> Bolt a thick plywood floor to the top of the iron hunk, and attach
>>> the clocks to this floor.
>>>
>>> Joe Gwinn
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>>> an email to time-nuts-leave at lists.febo.com
>>> To unsubscribe, go to and follow the instructions there.
>>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
> ------------------------------
>
> Message: 12
> Date: Thu, 9 Sep 2021 13:57:44 -0600
> From: John Marvin <jm-tnut at themarvins.org>
> Subject: [time-nuts] Re: in-ground clock room
> To: time-nuts at lists.febo.com
> Message-ID: <7c02f7ff-8cd7-e2b2-88af-16f6ee138466 at themarvins.org>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hmm, this list isn't called time-science, time-research, time-hardware,
> or time-trivia. It's called time-nuts. This is probably one of the most
> on topic (and fun) posts I've seen on this list. :)
>
> Regards,
>
> John
>
>> On 9/8/2021 7:54 PM, Tom Van Baak wrote:
>>
>> In case this gets too off-topic for time-nuts, off-list email to me is
>> fine (tvb at leapsecond.com).
>>
>> Thanks,
>> /tvb
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe
>> send an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
>
> ------------------------------
>
> Message: 13
> Date: Thu, 09 Sep 2021 13:57:30 -0800
> From: "Bill Beam" <wbeam at gci.net>
> Subject: [time-nuts] Re: [time nuts] Re: in-ground clock room
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at lists.febo.com>
> Message-ID: <05.1F.05200.1538A316 at smtp02.beryl.bos.sync.lan>
> Content-Type: text/plain; charset="us-ascii"
>
> --Original Message Text---
> From: Tom Van Baak
> Date: Thu, 9 Sep 2021 04:44:22 -0700
>
>
>
> Hi Bill,
>
> I'd like undisturbed on the order of several months or years. Yes, earthquakes are possible but they are rare here and interesting so that's
> ok. Here's a once-in-a-decade one that I captured a few years ago:
>
> https://url.emailprotection.link/?bdmFbtBVI5fRq-9wNeYkQ-gFamK1O8vBt3YAwjEUQaSUMHPHLx-i6bKvykxCz-00ThdyGMxzxk6o8IrmSaUTCxvJs0WcGPc8YKQXXSuyy8vAq8OBpMvaoBVHqIvOyCFuf
>
> The main thing is to avoid "cultural noise" -- local seismic activity caused by cars, trucks, doors opening and closing, people walking, A/C or
> mechanical appliances going on and off, etc. This is best done by locating the clocks away from roads, away from the house, in a solid
> compartment weighing many tons, underground in virgin soil or bedrock.
>
> Hi Tom,
>
> A "compartment weighing many tons" is a low pass filter good against "cultural noise" but not so good against earth quake or earth tide
> noise. A "compartment weighing many tons" is strongly coupled to the earth. The opposite approach is to uncouple from the earth as
> much as possible. Your earthquake enviornment in the Pacific northwest is similar to here in Alaska. Your precision pendulum clock
> is good enough to respond to monthly/daily earth tides. There is a 'catch 22' in trying to protect a pendulum clock. The pendulum
> depends on constant acceleration of gravity. It ain't constant. If g varies or is noisy by one part in N then that sets the point of diminishing
> return in your protection efforts.
>
> Bill
>
> /tvb
> On 9/8/2021 7:36 PM, Bill Beam wrote:
>
> Tom,
>
> How long do you expect your proposed voult to go undisturbed?
> I have several pendulum clocks. They are disturbed every couple of months
> by earth quakes. By disturbed, I mean pendulum banging against the case walls....
> Any ground motion that can be felt will upset the clocks. Often the clocks will
> signal an earth quake that is not felt.
>
> Good luck.
>
>
>
>
> Bill Beam
> NL7F
>
>
>
>
> Bill Beam
> NL7F
>
>
>
> ------------------------------
>
> Message: 14
> Date: Thu, 9 Sep 2021 15:17:22 -0700
> From: "Lux, Jim" <jim at luxfamily.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: time-nuts at lists.febo.com
> Message-ID: <dbb895a4-371c-81bb-2ae0-7a982274642d at luxfamily.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
>> On 9/8/21 6:54 PM, 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.
>>
> A few years back, we were looking at building a "test rubble pile" for
> search and rescue applications (actually for testing equipment that
> would be used for this).
>
> For the depths you're talking about (few meters) the easiest approach is
> to get someone with a backhoe to dig a pit, then use the backhoe to
> carry the precast vault, drop it in, and you're done. If you were going
> more than "backhoe depth" you're looking at something like an auger, and
> they can drill any diameter (up to about 4 feet) and any depth, as long
> as they can get the truck into position (same as the backhoe).
>
> I went around looking at the precast concrete vendors - they're
> available in any size you want. You can also just sink a drain pipe of
> any size vertically, and fill the bottom with concrete. The vaults often
> come with "knockouts" - places where you can bring conduit in by
> knocking out the plug of concrete (it's cast with a thin ring, so you
> hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
> seal is done with a variety of goops. Some of the ones I've seen look
> like tar (the same stuff used to fix roads, roofs, shower pans), others
> use some sort of foam.
>
> The prices for this stuff are fairly standardized - your local utility
> or roads department probably has a "standard bid list" for most of the
> more common items that they use for doing estimates. Caltrans certainly
> does (a 48" precast concrete manhole is about $1500). So that gives you
> a ballpark when you start calling vendors. The big driver for most
> people in a "residential" environment would be access. It's one thing
> to have a double flatbed show up with a bunch of concrete pipe on it at
> a business, totally another on a winding residential street. We had
> stuff delivered on a flatbed truck with a small crane - but they could
> just pull up to the site, sling the vault, and lower it to the ground,
> and then the backhoe guy moved it. Going up a driveway, around the
> corner, avoiding the fence, etc. would be different. Or, A *really big*
> crane - I've seen that done - 80 or 100 foot boom in the street - they
> pick the load up, lift it up and over the house and place it in the back
> yard.
>
> https://url.emailprotection.link/?b4vU3x8i5fTvyzlQz6y9GOCtVn2tdfzrFSR54T5cRl_uAtXpIOtBBqqwnV4vvFy1BmFE0feOJrmWRAW6qHW8lkO6-L7cdYeUDZSpmMaEHfuxRGyelFEjAK6MatgClTQ9f
>
> https://url.emailprotection.link/?bMgheXmXOXXWGkEGh8fPBr6lrAr7Q86Lv2pzXVXq2h2r6_ZhJY1XlJ6RJXJzCSe7od5P0dH6_AGbo4tSHU_9d3dnFyDDiNcXCASM95efa7VWFoeLurCDQb4g3_4LRgWkW
>
> https://url.emailprotection.link/?bVk3-XAtcEXlrmrcOdaAPyyNHDetyE--dojTOGrR3Q1jmKx0N586lNzcUPLMddNAV7AFKoc4NMWmZVMAgYIkuvHw_TAaIGWVfhJ4hoixRP-POCndpSfmCsbHIJwmgK3qa
>
> Google "precast concrete manhole" and select accordingly.
>
>
>
> You're looking at the "more than $1000 probably less than $10k" range,
> all done in a day, plus a day of prep and a day of cleanup.
>
> Backhoes (in SoCal) are going for $300-500/day plus the operator
> ($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
> a rookie, but digging a hole is pretty easy to learn on your own. And I
> just looked it up, the smaller skid-steer bobcat type could probably dig
> a 2 meter deep hole, and you're less likely to do major damage like you
> can with a full sized unit.
>
> Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
> $1005/week
>
> https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
> You might find someone who's usually doing stuff like pools and spas,
> and will dig your hole for you. In any case, probably not more than $1000
>
>
> One other source for design is "storm shelters" - FEMA has published
> pre-engineered designs for a variety of inground shelters (often,
> installed below a garage)
>
>
> One final thing - even if it's waterproofed, it *will collect water*
> either by condensation or seepage. You might need to make your clock
> vault have some sort of dehumidifier and/or sump pump.
>
>
> The other alternative is to "build a basement" - dig the hole by hand,
> pour a slab, and either pour walls or stack blocks and pour into the
> cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
> blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
> That's big enough to stand in, but there is a significant cave-in
> hazard, If you're down 2 meters, and the side collapses on you, you'll
> probably die before they can dig you out. Or, your soil is sturdy
> enough, you manage the risk.
> I don't think you could dig 2 meters down with one of those small bobcat
> backhoes or excavators, you'd have to dig a ramp, stack your blocks,
> then backfill.
>
>
>> In case this gets too off-topic for time-nuts, off-list email to me is
>> fine (tvb at leapsecond.com).
>>
>> Thanks,
>> /tvb
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe
>> send an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
>
> ------------------------------
>
> Message: 15
> Date: Thu, 9 Sep 2021 18:03:08 -0500
> From: "Graham / KE9H" <ke9h.graham at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CAPyJ-YWhz_C7r=meJ91skKMeQtBA7rRXVKZAtByCA3cARqo_Qw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Sounds like we need a volunteer time-nut with motion picture camera
> capability to document this event.
> --- Graham
>
>> On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim <jim at luxfamily.com> wrote:
>>
>>> On 9/8/21 6:54 PM, 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.
>>>
>> A few years back, we were looking at building a "test rubble pile" for
>> search and rescue applications (actually for testing equipment that
>> would be used for this).
>>
>> For the depths you're talking about (few meters) the easiest approach is
>> to get someone with a backhoe to dig a pit, then use the backhoe to
>> carry the precast vault, drop it in, and you're done. If you were going
>> more than "backhoe depth" you're looking at something like an auger, and
>> they can drill any diameter (up to about 4 feet) and any depth, as long
>> as they can get the truck into position (same as the backhoe).
>>
>> I went around looking at the precast concrete vendors - they're
>> available in any size you want. You can also just sink a drain pipe of
>> any size vertically, and fill the bottom with concrete. The vaults often
>> come with "knockouts" - places where you can bring conduit in by
>> knocking out the plug of concrete (it's cast with a thin ring, so you
>> hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
>> seal is done with a variety of goops. Some of the ones I've seen look
>> like tar (the same stuff used to fix roads, roofs, shower pans), others
>> use some sort of foam.
>>
>> The prices for this stuff are fairly standardized - your local utility
>> or roads department probably has a "standard bid list" for most of the
>> more common items that they use for doing estimates. Caltrans certainly
>> does (a 48" precast concrete manhole is about $1500). So that gives you
>> a ballpark when you start calling vendors. The big driver for most
>> people in a "residential" environment would be access. It's one thing
>> to have a double flatbed show up with a bunch of concrete pipe on it at
>> a business, totally another on a winding residential street. We had
>> stuff delivered on a flatbed truck with a small crane - but they could
>> just pull up to the site, sling the vault, and lower it to the ground,
>> and then the backhoe guy moved it. Going up a driveway, around the
>> corner, avoiding the fence, etc. would be different. Or, A *really big*
>> crane - I've seen that done - 80 or 100 foot boom in the street - they
>> pick the load up, lift it up and over the house and place it in the back
>> yard.
>>
>> https://url.emailprotection.link/?b4vU3x8i5fTvyzlQz6y9GOCtVn2tdfzrFSR54T5cRl_uAtXpIOtBBqqwnV4vvFy1BmFE0feOJrmWRAW6qHW8lkO6-L7cdYeUDZSpmMaEHfuxRGyelFEjAK6MatgClTQ9f
>>
>> https://url.emailprotection.link/?bMgheXmXOXXWGkEGh8fPBr6lrAr7Q86Lv2pzXVXq2h2r6_ZhJY1XlJ6RJXJzCSe7od5P0dH6_AGbo4tSHU_9d3dnFyDDiNcXCASM95efa7VWFoeLurCDQb4g3_4LRgWkW
>>
>> https://url.emailprotection.link/?bVk3-XAtcEXlrmrcOdaAPyyNHDetyE--dojTOGrR3Q1jmKx0N586lNzcUPLMddNAV7AFKoc4NMWmZVMAgYIkuvHw_TAaIGWVfhJ4hoixRP-POCndpSfmCsbHIJwmgK3qa
>>
>> Google "precast concrete manhole" and select accordingly.
>>
>>
>>
>> You're looking at the "more than $1000 probably less than $10k" range,
>> all done in a day, plus a day of prep and a day of cleanup.
>>
>> Backhoes (in SoCal) are going for $300-500/day plus the operator
>> ($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
>> a rookie, but digging a hole is pretty easy to learn on your own. And I
>> just looked it up, the smaller skid-steer bobcat type could probably dig
>> a 2 meter deep hole, and you're less likely to do major damage like you
>> can with a full sized unit.
>>
>> Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
>> $1005/week
>>
>>
>> https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~
>> You might find someone who's usually doing stuff like pools and spas,
>> and will dig your hole for you. In any case, probably not more than $1000
>>
>>
>> One other source for design is "storm shelters" - FEMA has published
>> pre-engineered designs for a variety of inground shelters (often,
>> installed below a garage)
>>
>>
>> One final thing - even if it's waterproofed, it *will collect water*
>> either by condensation or seepage. You might need to make your clock
>> vault have some sort of dehumidifier and/or sump pump.
>>
>>
>> The other alternative is to "build a basement" - dig the hole by hand,
>> pour a slab, and either pour walls or stack blocks and pour into the
>> cavities. 1x1x2 meters is sort of doable.. figure standard 8x16"
>> blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft.
>> That's big enough to stand in, but there is a significant cave-in
>> hazard, If you're down 2 meters, and the side collapses on you, you'll
>> probably die before they can dig you out. Or, your soil is sturdy
>> enough, you manage the risk.
>> I don't think you could dig 2 meters down with one of those small bobcat
>> backhoes or excavators, you'd have to dig a ramp, stack your blocks,
>> then backfill.
>>
>>
>>> In case this gets too off-topic for time-nuts, off-list email to me is
>>> fine (tvb at leapsecond.com).
>>>
>>> Thanks,
>>> /tvb
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe
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>
> ------------------------------
>
> Message: 16
> Date: Thu, 9 Sep 2021 20:47:29 -0400
> From: Ben Bradley <ben.pi.bradley at gmail.com>
> Subject: [time-nuts] Re: in-ground clock room
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> Message-ID:
> <CA+wjhVsKT67AOghjXT91LwupF0FG3v=XiQEX4q0-2jVRQYHXnw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> I've seen discussion of making a seismic vault (though not sure if
> they used that name, making it harder to find in the haystack of
> posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if
> this is helpful:
> https://url.emailprotection.link/?bj4D6X82wPC9xeltcsFCTXzK_O0xDS6ilwrNrr973O-CWyDkiYmR6AtIlije3Uhl-EhDjaWB722xAQMGo5pYzKsypwE_cPrdr7cPkFE8GrFQ48neYZCy5Hu7yuZjpSqlB
>
> For possible immunity from earthquakes, LIGO uses some quite complex
> control and feedback systems to hang its mirrors so that mild
> earthquakes and local noise won't affect them. From what I've seen
> over the years a lot of this info has been published, but I imagine it
> would be quite expensive to reproduce. Maybe some sort of Ligo Lite
> system would be feasible.
>
>> On Thu, Sep 9, 2021 at 10:13 AM Brent <brent.evers at gmail.com> wrote:
>>
>> Seismic vaults are built similar to your requirements. I suggest looking
>> up the Earthscope program - there should be info out on the web as to how
>> their vaults were designed, but in a nutshell, dig a hole, put some gravel
>> in the bottom, place a large culvert on end in the hole, pour a few inches
>> of concrete in the culvert, put instrumentation in a pedestal inside, run
>> power and comms, put a bilge pump and outflow pipe in it on the floor
>> (below pedastal), and put a cap on the whole thing. Those were then
>> re-buried, but that prevents easy access (although it probably improves
>> temperature stability). A septic tank would be larger, but more effort, and
>> may expose more surface area to the sun (temp variation).
>>
>> I've been in various seismic vaults and they can vary from very extravagant
>> to downright crude.
>>
>>
>>
>>> On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>>>
>>> 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://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~
>>>>
>>>> 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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>>> send an email to time-nuts-leave at lists.febo.com
>>>> To unsubscribe, go to and follow the instructions there.
>>> _______________________________________________
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>> _______________________________________________
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> ------------------------------
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