First the lubber line can be adjusted so that it is aligned with the direction in which the ship travels, then the effects of permanent magnets can be corrected for by small magnets fitted within the case of the compass.

It is also usually necessary to have a small magnet to bias the magnetostrictive material into its operating range.

Now when you're in an fMRI scanner, you're in a big magnet that's aligning your molecules in certain areas.

And we had custom espresso cups made that hide a magnet inside, and make those compasses go crazy, always centering on them.

Tom Shannon shows off his gravity defying, otherworldly sculpture made of simple, earthly materials that floats and spins like planets on magnets and suspension wire. It's science inspired art at its most heavenly.

Deviation refers to the response of the compass to local magnetic fields caused by the presence of iron and electric currents one can partly compensate for these by careful location of the compass and the placement of compensating magnets under the compass itself.

Compasses are particularly difficult to use accurately in or near trucks, cars or other mechanized vehicles even when corrected for deviation by the use of built in magnets or other devices.