[time-nuts] Measurements

[Neville Michie]

Not only does it increase the least count of the scale, but it tends  
to average out the errors of the scale
like ellipticity and eccentricity, because there is always  
360.000000000000000000000000000000 degrees in a full circle.
cheers, Neville Michie




On 22/08/2009, at 7:33 PM, Magnus Danielson wrote:

> Sanjeev Gupta wrote:
>> 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_repetition
>>> skreis.htm<http://www.bistumsmuseen-regensburg.de/html/ 
>>> ausstellungen_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.
>
> Cool. I completely understands it yeat, it was new to me. So now I  
> know what I learned today.
>
> Thanks Sanjeev!
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.