Date:         Thu, 16 May 2002 21:42:07 +1000
Reply-To:     Andrew Jack <andrewxp@AJ.DNSALIAS.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Andrew Jack <andrewxp@AJ.DNSALIAS.NET>
Subject:      Origin of the Metre/Meter (Was: Re: Warning!!!  Check Your
              Speedometer - What a Sad, Sad Example)
Content-Type: text/plain; charset="iso-8859-1"

> Actually I believe the original definition was in terms of the earth's
> circumference, just like the nautical mile. <g>

Nope, actually it was defined in 1791 as one ten-millionth of the length of
the earth's meridian along a quadrant (one fourth the circumference of the
earth).  Thus, the meter was intended to equal 10-7 or one ten-millionth of
the length of the meridian through Paris from pole to the equator. However,
the first prototype was short by 0.2 millimeters because researchers
miscalculated the flattening of the earth due to its rotation. Still this
length became the standard.

Various new definitions were adopted over time, until in 1983 the CGPM
replaced the previous definitions by the following definition:

** The meter is the length of the path travelled by light in vacuum during a
time interval of 1/299 792 458 of a second. **

Source: http://www.physics.nist.gov/cuu/Units/meter.html

Regards
Andrew

(whose speedometers <note it's not a speedomile> all read in kilometres per
hour - except the Air Speed Indicator in the airplane - which reads in
knots....)

----- Original Message -----
From: "David Beierl" <dbeierl@ATTGLOBAL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, May 16, 2002 7:18 PM
Subject: Re: Warning!!! Check Your Speedometer - What a Sad, Sad Example


> At 04:42 AM 5/16/2002, Andrew Grebneff wrote:
> >Matric is the ONLY system which makes any sense. The meter itself may
> >be arbitrary in length, but the other measures are all based directly
> >on it.
>
> Actually I believe the original definition was in terms of the earth's
> circumference, just like the nautical mile. <g>
>
> d
>
>
> --
> David Beierl - Providence, RI
>   http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage"
> '85 GL "Poor Relation"
>