On Mar 19, 2:42*pm, Joe wrote:

A problem that is common in our locale is that the
early surveyors were evidently sloppy with their magnetic North
settings. When I wanted a precise location for a fence around the
first house I bought, the surveyors discovered that the east-west line
was nearly 2' off to the east.

Magnetic north declination is constantly shifting. To determine a
magnetic
north setting from years ago vs a magnetic north recheck of that
setting
today would require a correction factor for the shifting of the
field. IIRC,
the true north pole is about 100+ miles from the magnetic north pole.
True
north is determined by solar measurements rather than compass.

KC