[time-nuts] Shortt Clock Recent Measurements

[paul swed]

Been reading and not getting tangled up. Agree that it seems like a
reasonable subject. Though I have no pendulum clocks. I was struck by their
beauty up in Canada at TVAs television studios. On the wall was this
amazing clock on a huge slab of metal. All it needed was a battery. Other
then that it was clean and gently pushing the pendulum seemed to make it
work. It was to go into there historical museum someday.
I always thought invar was the magic metal. Quartz rod? You can get those
at some reasonable cost?
What I am curious about is there a wear mechanism on these really good
clocks.
Does the pendulum just swing on a bending piece of metal or on a bearing?

To the technical side isn't it sort of cheating the wonder of the clock
using gps correction. I mean at that point there is no point.
I am asking these questions because its sort of the thing I would not mind
crafting.
Regards
Paul.
WB8TSL


On Tue, Dec 10, 2013 at 7:15 PM, Don Latham <djl at montana.com> wrote:

> Brian and Tom: I second as well. It's important to be aware of the past.
> Somewhere around here is a 4 ft length of Invar, 1/2 in. diameter. It
> was supposed to be a pendulum rod. However, I did read that Invar
> displays rearrangement noise of some kind. Kinda like the jumps in a
> quartz element?
> I think if I were to start designing, I'd use a quartz rod instead,
> coefficient of thermal expansion is smaller. I'll bet that a large
> majority of time-nuts have at least read about pendulum timekeepers...
> The Smithsonian has a Schortt clock, as well as a couple of others. I am
> sad that they aren't running.
> Don
>
> Brian, WA1ZMS
> > FWIW....
> >
> > Let me just second Tom's last comment:
> > "Some of you readers might wonder why in this GPS age, two time nuts,
> > each
> > with plenty of atomic clocks at home, would be talking about vintage
> > pendulum clocks. It turns out that pendulum clocks are still extremely
> > interesting timekeepers, from an experimental, scientific, and
> > historical
> > perspective."
> >
> > About 2 years ago the Time Nut in me became very interested in pendulum
> > clocks that were made in my home town in Vermont going back as far as
> > 1797.
> > I now own several and a project is to take one of them that has a
> > dead-beat
> > escapement (often noted for its better "accuracy" display of seconds
> > with an
> > 10 inch sweep hand in its day) into the 21st century with frequency
> > locking
> > of the pendulum to the 1PPS from one of my GPS receivers.
> >
> > Also....An antique clock dealer who is friend of mine was well pleased
> > with
> > TVB's talk at a recent time conference on the West Coast.  So it is a
> > mix of
> > old and new for me at this point.   Apologies if this goes OT.
> >
> > Regards,
> > -Brian, WA1ZMS/4
> >
> >
> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> > Behalf Of Tom Van Baak
> > Sent: Tuesday, December 10, 2013 5:48 PM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] Shortt Clock Recent Measurements
> >
> >> The Wiki page for the Shortt pendulum clock has a "Recent
> >> Measurements"
> > (1984)  paragraph that's in error.
> >> http://en.wikipedia.org/wiki/Shortt-Synchronome_clock#Recent_accuracy_
> >> measurement
> >>
> >> While it's probably true that the clock is stable to 200 uS per day
> >> (i.e. 2E-9) I believe Alfred Loomis discovered the effect of the moon
> >> on
> > this clock a long time ago.
> >
> > Hi Brooke,
> >
> > The wiki page is correct. The heading is "Recent Measurements" and
> > Pierre
> > Boucheron's 1984 effort certainly qualifies. Note the wiki doesn't claim
> > Boucheron was the first. In fact, even 30 years old, it is still the
> > most
> > recent, and the only Shortt experiment for which we have raw data. See
> > http://leapsecond.com/pend/shortt/ for details.
> >
> > One could try claiming that Loomis was the first to make detailed
> > measurements of a Shortt, but it would take some digging to prove he was
> > "first" and not just "one of the first". I mean, if you look at the list
> > of
> > who received the one hundred Shortt's that were manufactured, many
> > laboratories had more than one, not to mention the ones that William
> > Shortt
> > himself owned at the factory. Certainly there was a lot of time
> > measurement
> > going on in the 20's and 30's. It would take a lot of work to uncover
> > what
> > was known by whom and when. Or who published first or not.
> >
> > I think Loomis took it a wonderful extreme with his spark chronograph
> > and
> > quartz oscillator via telephone time transfer setup. And that be bought
> > three clocks at once is classic and inspiring to any time nut! So I
> > agree,
> > Loomis deserves mention on the Shortt wiki page.
> >
> > Unrelated to gravity and tides, is the role that vacuum pendulum and
> > ovenized quartz clocks had in confirming that earth rotation was itself
> > irregular at the millisecond level. Credit for that usually goes to
> > Scheibe
> > and Adelsberger in the late 30's, not Shortt or Loomis. And that of
> > course
> > blends into the story of the leap second...
> >
> > See my scan/OCR historical pendulum collection:
> > http://leapsecond.com/pend/pdf/ And my own precision pendulum-nut
> > articles:
> > http://leapsecond.com/hsn2006/
> >
> > Some of you readers might wonder why in this GPS age, two time nuts,
> > each
> > with plenty of atomic clocks at home, would be talking about vintage
> > pendulum clocks. It turns out that pendulum clocks are still extremely
> > interesting timekeepers, from an experimental, scientific, and
> > historical
> > perspective.
> >
> > /tvb
> >
> >
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> >
>
>
> --
> "The power of accurate observation is commonly called cynicism by those
> who have not got it."
>  -George Bernard Shaw
>
>
> Dr. Don Latham AJ7LL
> Six Mile Systems LLC
> 17850 Six Mile Road
> POB 134
> Huson, MT, 59846
> VOX 406-626-4304
> Skype: buffler2
> www.lightningforensics.com
> www.sixmilesystems.com
>
>
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