Magnetic Declination

by Matt Hopkinson

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I was amazed when I sat down to create a table of declinations for my big trip from Quebec to Penobscot Bay. From central Massachusetts where I live, to Yarmouth Maine, I have to adjust the declination from around 15.5 degrees to about 20 degrees over a distance of about 150 miles. I forgot this step once, and had no idea where to find the start of that portage trail on the far side of the lake.

I thought I was going nuts when I read the declinations off the various maps and found it only varied by about two tenths of a degree for this 500 mile trip. I was relieved when I looked at a map of declinations for the whole continent. It seems our trip is running roughly parallel to the magnetic lines of force, while driving from Massachusetts to Maine is sorta perpendicular.

Ain't science grand?

[More on the Flight from Quebec]