On topographic maps, can i compare the secondary highway lines with the scales?
Alternating lines are not related. However, if you want to determine distance you can bring some string to measure with, using the scales.
Does anyone know how to find magnetic declination over time?
Like if they say find the declination in 2011. How do u do that?
I'm not sure. I'd do some research. Magnetic declination is not the same all over the world... wow, I seriously don't know. Now I'm going to have to do some research.