Midwest

[Dave Wilton]

-----Original Message-----
From: American Dialect Society [mailto:ADS-L at LISTSERV.UGA.EDU]On Behalf
Of James A. Landau
Sent: Friday, February 22, 2002 7:16 PM
To: ADS-L at LISTSERV.UGA.EDU
Subject: Re: Midwest

>Aha! A chance to bore everybody:

>The center of the United States is in Kansas, specifically at a point a
>little west of Topeka known as "Mead's Ranch".  There is a monument there
>marking the exact geographical center of the United States.  (More
precisely,
>of the "lower 48".  If you add in Alaska, the geographic center of the US
is
>somewhere in the Dakotas.)

>And the significance of Mead's Ranch?  All latitudes and longitudes in the
>United States are measured from that point.

With the advent of satellite mapping techniques this is no longer true.
Spheroids are no longer measured from points on the earth's surface, but
rather from a point in space and a single datum is used for the entire earth
instead of a variety of local ones. The Global Positioning System (GPS) uses
the World Geodetic System of 1984 (WGS84) instead of the North American
Datum of 1927 (NAD27), which is based on Clarke's 1866 spheroid and Mead's
Ranch, or other local spheroids and associated datums.

To bring the discussion back around to language, interestingly in Geodetics
the plural of datum is apparently datums and not data. A datum defines a
spheroids position relative to the center of the earth. NAD27 and WGS84 are
datums, not data.

(I once managed the development of a software mapping system for the DoD and
some of the Geodetics wore off on me.)