[time-nuts] Clock Calibration
List, I was reading some of the history of mechanical clocks and was astonished to see that one guaranteed its accuracy to 2 milliseconds per day! (And it was) Now this same clock when tested with modern equipment tested to be accurate to 200 micro-seconds per day. Astonishing! This got to wondering how the heck they were able to calibrate a clock to milliseconds per day back then? And as extension to that question, how do they prove the accuracy of F1 or other similar time standards? Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
Hi Perrier: When was this? Do you have a URL? Have Fun, Brooke Clarke http://www.PRC68.com Perry Sandeen wrote: List, I was reading some of the history of mechanical clocks and was astonished to see that one guaranteed its accuracy to 2 milliseconds per day! (And it was) Now this same clock when tested with modern equipment tested to be accurate to 200 micro-seconds per day. Astonishing! This got to wondering how the heck they were able to calibrate a clock to milliseconds per day back then? And as extension to that question, how do they prove the accuracy of F1 or other similar time standards? Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
Boy I sure don't know but. I could make some assumptions especially if it were 100 years ago. I might guess its either a sun or star track and the fact that exactly 24 hours later it crossed. Granted the clock could be adjusted so that its tick would exactly cross. Most likely a light/candle and a small mirror on the pendulum This would not account for any of the effects we consider today. Just my crazy useless way of thinking. Regards Paul On Thu, Jan 27, 2011 at 3:55 PM, Perry Sandeen wrote: > List, > > I was reading some of the history of mechanical clocks and was astonished > to see that one guaranteed its accuracy to 2 milliseconds per day! (And it > was) Now this same clock when tested with modern equipment tested to be > accurate to 200 micro-seconds per day. Astonishing! > > This got to wondering how the heck they were able to calibrate a clock to > milliseconds per day back then? > > And as extension to that question, how do they prove the accuracy of F1 or > other similar time standards? > > Regards, > > Perrier > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
Hi If you go by Wikipedia, 10 ms per day was considered pretty good in 1909. Shortt clocks came along in 1929 and are mentioned as 1 second per year. I suspect the 2 ms / day and 1 sec per year numbers are both referring to a Shortt. Simple answer is that all of this came along after you had electronics to compare stuff with. Calibration times were in months. Deviations between clocks in an ensemble were used to estimate shorter time periods. I don't find it to unbelievable that you could time an astronomical event to ~ 0.1 seconds or better without anything very fancy being involved. If you wanted to automate it, light sensors date back into the 1850's. Either way you could get data in less than a year that would confirm / deny your accuracy. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, January 27, 2011 4:13 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Clock Calibration Boy I sure don't know but. I could make some assumptions especially if it were 100 years ago. I might guess its either a sun or star track and the fact that exactly 24 hours later it crossed. Granted the clock could be adjusted so that its tick would exactly cross. Most likely a light/candle and a small mirror on the pendulum This would not account for any of the effects we consider today. Just my crazy useless way of thinking. Regards Paul On Thu, Jan 27, 2011 at 3:55 PM, Perry Sandeen wrote: > List, > > I was reading some of the history of mechanical clocks and was astonished > to see that one guaranteed its accuracy to 2 milliseconds per day! (And it > was) Now this same clock when tested with modern equipment tested to be > accurate to 200 micro-seconds per day. Astonishing! > > This got to wondering how the heck they were able to calibrate a clock to > milliseconds per day back then? > > And as extension to that question, how do they prove the accuracy of F1 or > other similar time standards? > > Regards, > > Perrier > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
Hi This is an interesting concept of measuring or comparing without electronics. Dont forget the scientists of former eras has some quite inovative bits of kit. the CRT dated from the 1920 but Victorians used a sooted glass slide carried on a small trolley that was moved by a falling weight.a storage 'scope forsooth :-)) I believe you will find Bell used a similar item in his speech investigations. Also, yes time was cheaper then so a test period of days would be acceptable..it only very recenly we have become so impatient :-)) It would probably be relatively easy to divide the swing of a long pendulum up in to 10ths or even 20th of a second and your reference would be a transit telescope, or, I believe, the Moon and a church steeple ?? was that Harrisons early work with the all wooden mechanisms? Alan G3NYK - Original Message - From: "Bob Camp" To: "'Discussion of precise time and frequency measurement'" Sent: Thursday, January 27, 2011 9:56 PM Subject: Re: [time-nuts] Clock Calibration > Hi > > If you go by Wikipedia, 10 ms per day was considered pretty good in 1909. > Shortt clocks came along in 1929 and are mentioned as 1 second per year. I > suspect the 2 ms / day and 1 sec per year numbers are both referring to a > Shortt. > > Simple answer is that all of this came along after you had electronics to > compare stuff with. Calibration times were in months. Deviations between > clocks in an ensemble were used to estimate shorter time periods. > > I don't find it to unbelievable that you could time an astronomical event to > ~ 0.1 seconds or better without anything very fancy being involved. If you > wanted to automate it, light sensors date back into the 1850's. Either way > you could get data in less than a year that would confirm / deny your > accuracy. > > Bob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of paul swed > Sent: Thursday, January 27, 2011 4:13 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Clock Calibration > > Boy I sure don't know but. > I could make some assumptions especially if it were 100 years ago. I might > guess its either a sun or star track and the fact that exactly 24 hours > later it crossed. Granted the clock could be adjusted so that its tick would > exactly cross. Most likely a light/candle and a small mirror on the > pendulum This would not account for any of the effects we consider > today. Just my crazy useless way of thinking. > Regards > Paul > > On Thu, Jan 27, 2011 at 3:55 PM, Perry Sandeen wrote: > > > List, > > > > I was reading some of the history of mechanical clocks and was astonished > > to see that one guaranteed its accuracy to 2 milliseconds per day! (And it > > was) Now this same clock when tested with modern equipment tested to be > > accurate to 200 micro-seconds per day. Astonishing! > > > > This got to wondering how the heck they were able to calibrate a clock to > > milliseconds per day back then? > > > > And as extension to that question, how do they prove the accuracy of F1 or > > other similar time standards? > > > > Regards, > > > > Perrier > > > > > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
On Thu, Jan 27, 2011 at 12:55 PM, Perry Sandeen wrote: > ...how the heck they were able to calibrate a clock to milliseconds per day > back then? Let it run for 1,000 days, then you only need to be able to measure to the nearest second to get to ms per day. Or maybe you can measure to 0.1 seconds so it only takes 100 days. The trouble is that using this method you don't know the average error. A good example is an eccentric gear that makes a second hand run fast then slow but if averaged over a long period is near perfect. I doubt they were able to catch stuff like that. -- = Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clock Calibration
Ah now from time nuttery to horology. There are those of us who tinker with
analog clocks as well...
Generally we 'beat' clocks against 'standard' clocks or more recently a pc
application with a microphone over long periods of time generally at least a
week and commonly a month.
Scott
Sent from my Verizon Wireless BlackBerry
-Original Message-
From: Chris Albertson
Sender: time-nuts-boun...@febo.com
Date: Thu, 27 Jan 2011 15:52:49
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Clock Calibration
On Thu, Jan 27, 2011 at 12:55 PM, Perry Sandeen wrote:
> ...how the heck they were able to calibrate a clock to milliseconds per day
> back then?
Let it run for 1,000 days, then you only need to be able to measure to
the nearest second to get to ms per day. Or maybe you can measure to
0.1 seconds so it only takes 100 days.
The trouble is that using this method you don't know the average
error. A good example is an eccentric gear that makes a second hand
run fast then slow but if averaged over a long period is near perfect.
I doubt they were able to catch stuff like that.
--
=
Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Clock Calibration
I have a little piezo sounder on the PPS from a t/bolt. It runs off a
cmos gate, I can not remember whether I put some pulse stretching in,
but it needs an on/off switch or the ticking will drive you mad.
This is great to use with the UTC time on LH. You look at the time,
then keep counting with the audible ticks to guide you while you
check your analogue clocks.
I also have a BCD counter dividing the 10MHz from the T/Bolt that
drives a time display. As well, the milliseconds, 100 microseconds,
or 10s of microseconds are counted and
can be latched by a proximity switch into a homebrew BCD DAC which is
recorded by a HOBO logger to give very accurate logging of phase for
whichever clock the proximity is clipped to.
It is all low power, saves serious frequency counters, PC et. al. so
you can log continuously for years without a major power bill.
cheers, Neville Michie
On 30/01/2011, at 4:16 AM, scmcgr...@gmail.com wrote:
Ah now from time nuttery to horology. There are those of us who
tinker with analog clocks as well...
Generally we 'beat' clocks against 'standard' clocks or more
recently a pc application with a microphone over long periods of
time generally at least a week and commonly a month.
Scott
Sent from my Verizon Wireless BlackBerry
-Original Message-
From: Chris Albertson
Sender: time-nuts-boun...@febo.com
Date: Thu, 27 Jan 2011 15:52:49
To: Discussion of precise time and frequency measurementn...@febo.com>
Reply-To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Clock Calibration
On Thu, Jan 27, 2011 at 12:55 PM, Perry Sandeen
wrote:
...how the heck they were able to calibrate a clock to
milliseconds per day back then?
Let it run for 1,000 days, then you only need to be able to measure to
the nearest second to get to ms per day. Or maybe you can measure to
0.1 seconds so it only takes 100 days.
The trouble is that using this method you don't know the average
error. A good example is an eccentric gear that makes a second hand
run fast then slow but if averaged over a long period is near perfect.
I doubt they were able to catch stuff like that.
--
=
Chris Albertson
Redondo Beach, California
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time-nuts
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