Two Antennas (was RE: "Blunkett u-turn on data privacy plans")

[Roland Perry]

In message <3E65D59B.16902.112C0D@localhost>, David Hansen 
<davidh@spidacom.co.uk> writes

>examples of spurious accuracy

Indeed, and if we are talking about surveying in the USA, depending on 
what you define as "level" [1] I think you can be plus or minus six feet 
by the time you get from one coast to the other.

[1] Do you walk across the USA with a spirit level, to get a 
"gravitational" level, or do you do something based on a spherical 
geometry and some agreed place for the centre of the earth. And GPS 
"ground level" is probably a third thing.
-- 
Roland Perry