Dear Pierre,
On 2010/10/20, at 00:27 , Pierre Abbat wrote:
The length of the pendulum in standard gravity is 993.621 mm. The
difference
between that and the meter bar would be immediately obvious to the
metrologists of the time,
The idea of "standard gravity" had not really developed in the 1780s
when Thomas Jefferson and the French "philosophes" began to address
this question. The French people did their pendulum experiments mostly
in Paris (with the Paris latitude and longitude, and elevation above
sea level). Jefferson, on the other hand, probably did his
experimentation at his home of Monticello in Virginia. However, it was
probably Jefferson who negotiated the idea of a pendulum at 45° North
latitude (and at sea level ??) and this definition then evolved into
the concept that we now know as "standard gravity".
whereas the difference between the fraction of the
meridian and the meter bar is less than a millimeter. (a(1) means
arctangent
of 1.)
9.80665/(a(1)*4)^2
.99362138556613170634
As they say in showman's circles, "Close, but no cigar!" I don't think
that the longitude measure was ever accepted by the Academy of Science
so they never recommended this definition to the French government.
Dunkirk to Barcelona is about 1/40, not 1/10, of the earth's
circumference.
Could I see your calculation, please. The road distance from
Barcelona to Dunkerque is 1329 kilometres, and I worked from there.
See http://maps.google.ca/maps/ms?ie=UTF8&om=1&oe=UTF8&msa=0&msid=102676733516280739492.000001124006a1f2543c7
Btw, my father said Calais to Perpignan; any idea where that rumor
started?
I think that this was part of the Frenchification of the metric system
over the years. Perpignan is on the French side of the Spanish-French
border so a nationalist in France could then claim that the metric
system was wholly French. This went with that other fallacy about the
measurement of the line of longitude that "passed through Paris"; a
direct line from Barcelona to Dunkerque goes close to, but not
through, Paris.
As you know the invention of the metric system by Bishop John Wilkins
occurred in England. The French philosophes in the Academy of Science
probably knew this as they were very keen in the 1790s to develop a
"decimal metric system" for the whole world. This is why they chose
the line from Dunkerque to Barcelona to give it some international
credibility (and it was the longest North-South line available to them
on land). It is also why they worked so closely with Benjamin Franklin
and Thomas Jefferson in the USA in developing the "decimal metric
system". See http://metricationmatters.com/docs/USAMetricSystemHistory.pdf
and why they put in considerable political effort to work with Sir
John Riggs Miller, a member of the UK government, to develop a joint
approach to measurement reform for the whole world.
Cheers,
Pat Naughtin
Author of the ebook, Metrication Leaders Guide, see
http://metricationmatters.com/MetricationLeadersGuideInfo.html
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