[time-nuts] Clock Calibration
lists at rtty.us
Thu Jan 27 21:56:09 UTC 2011
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
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
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at 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.
On Thu, Jan 27, 2011 at 3:55 PM, Perry Sandeen <sandeenpa at yahoo.com> wrote:
> 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?
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