Charlie Brown asked me on 2002-10-29:1502

Can you give me a comparison in length between the 1799 meter and
the 1983 meter?

The length of the metre has not changed since its original
definition.  However,  the precision with which it was defined was
increased with each redefinition.  The aim of each definition was to
place the length of the new metre in the middle of the zone of
uncertainty of the previous metre   It was not a new length, it was
the old length as nearly as could be determined.  Maurice Danloux
Dumesnils in his �tude Critique du Syst�eme M�triqe, 1962, gives a
chart of the various definition of the metre.  If I read his chart
correctly, it is
	Quarter of the meridian		1 in 8 000
	m�tre des Archives		1 in 100 000
	metre of 1889			1 in 10 000 000
	cadmium wavelength  		1 in 60 000 000
	krypton 86 wavelength		1 in 500 000 000

Joseph B. Reid
17 Glebe Road West
Toronto  M5P 1C8		Telephone 416-486-6071

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