[time-nuts] Measurements

Ulrich Bangert df6jb at ulrich-bangert.de
Sun Aug 23 09:14:12 UTC 2009


Sanjeev,

> That sounds like the Repeating Theodolite, used for the 
> survey from Dunkirk <-> Paris <-> Barcelona

Exactly!

Thanks for your help
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Sanjeev Gupta
> Gesendet: Samstag, 22. August 2009 10:56
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Measurements
> 
> 
> On Sat, Aug 22, 2009 at 15:19, Ulrich Bangert 
> <df6jb at ulrich-bangert.de>wrote:
> 
> >  Which in turn lead to the invention of a new class of surveyor 
> > instruments, which in turn enabled the French to measure 
> the distance 
> > from the equator to the north pole (assumed to be 1/4 of the 
> > circumference) with a precision that must be admired even 
> from a today 
> > point of view. I do not know the english term for it but in German 
> > these instruments are called "Repetitionskreis". You can 
> find a pictue 
> > of one here:
> >
> >
> > 
> http://www.bistumsmuseen-regensburg.de/html/ausstellungen_moenche_repe
> > tition
> > 
> skreis.htm<http://www.bistumsmuseen-regensburg.de/html/ausstel
> lungen_moenche_repetition%0Askreis.htm>
> >
> 
> That sounds like the Repeating Theodolite, used for the 
> survey from Dunkirk <-> Paris <-> Barcelona
> 
> http://en.wikipedia.org/wiki/Repeating_circle
> 
> The basic idea is to mark out repeatedly the angle to be 
> measured, but actually measure the sum, _only_ at the end, 
> which you then divide.  It gives you the arithmetic mean of 
> the value directly.  The major advantage over doing this 
> mechanically, rather than adding it up in your notebook, is a 
> that you have reduced the least-count of your graduated scale.
> 
> 
> -- 
> Sanjeev Gupta
> +65 98551208     http://www.linkedin.com/in/ghane
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