Just though I would share this with everyone. The compass was one of our first tools as land surveyors.
Understanding how it worked back then and now helps those who retrace old surveys.
This involved setting the declination on your compass then and understanding the changes now.Surveying with a compass has not been used in many years and may be becoming a lost art.
But todays surveyor needs to understand it and how it worked. So read how this Big Change has come about in these two reports on Magnetic north.