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 <df...@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
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