meter or metre (m)the metric and SI base unit of distance. Originally, the meter was designed to be one ten-millionth of a quadrant, the distance between the Equator and the North Pole. (The Earth is difficult to measure, and a small error was made in correcting for the flattening caused by the Earth's rotation. As a result, the meter is too short by a bit less than 0.02%. That's not bad for a measurement made in the 1790's.) For a long time, the meter was precisely defined as the length of an actual object, a bar kept at the International Bureau of Weights and Measures in Paris. In recent years, however, the SI base units (with one exception) have been redefined in abstract terms so they can be reproduced to any desired level of accuracy in a well-equipped laboratory. The 17th General Conference on Weights and Measures in 1983 defined the meter as that distance that makes the speed of light in a vacuum equal to exactly 299 792 458 meters per second. The speed of light in a ! vacuum, c, is one of the fundamental constants of nature. Since c defines the meter now, experiments made to measure the speed of light are now interpreted as measurements of the meter instead. The meter is equal to approximately 1.093 613 3 yards, 3.280 840 feet, or 39.370 079 inches. Its name comes from the Latin metrum and the Greek metron, both meaning "measure."
http://www.unc.edu/~rowlett/units/index.html Baron Carter Austin, TX -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of DASDBILL2 Sent: Tuesday, January 07, 2014 17:42 To: [email protected] Subject: Re: OT: SI units and precision The original definition of the meter/metre was a certain fraction of the circumference of the earth. Today the definition is a certain number of wave lengths of the orange light given off by Krypton 86 at a particular temperature (or something like that). The modern, atandard English foot was derived by adding the lengths of the first ten grown men who entered a particular church one particular day and then dividing that sum by ten. This latter method, of course, was not arbitrary, but was completely intuitive. Bill Fairchild Franklin, TN ----- Original Message ----- From: "John Gilmore" <[email protected]> To: [email protected] Sent: Tuesday, January 7, 2014 5:03:50 PM Subject: Re: OT: SI units and precision All conceptually adequate systems of measurement are in some sense arbitrary, whether they be the Système Internationale (SI) or one that uses the furlong, troy ounce and fortnight instead. That conceded, the SI is the one used internationally, i.e., almost everywhere outside the United States (and, of course, by the scientific community within it). Our persistence in using antique English units not quite consistently instead is a dubious example of American particularism, as quaint as our obdurate persistence in using 12-hour clock time and AM and PM, the later much misused because M has been forgotten/suppressed. Moreover, "preoccupation with multiples of ten" is not at all silly. Conversion errors are very much more common in mixed-radix systems than they are in the SI. I could go on: the definition of the meter is not based upon the putative circumference of the earth, etc., etc. I am reminded of Oscar Wilde's characterization of fox hunting. John Gilmore, Ashland, MA 01721 - USA
