If you have equipment/apparatus that is very sensitive to magnetic fields, even as weak as the earth's own magnetic field, it is possible to shield it from this. Magnetic fields consist of magnetic lines of force that from complete loops, that is, no magnetic line of force has an end. Because of this, it is NOT possible (by simple conventional means, anyway) to completely stop such fields like stopping a "bullet". Magnetic shielding, instead, provides a zone or region of space where even strong fields are significantly ("noticeably") weakened and retarded. To provide this, you would surround your apparatus with a single-piece container made of magnetic alloys and metals, like tin. Iron, nickel, etc.
FOR BEST RESULTS...:
We attempted to include a ruler in these photographs to show that one
must place such a toy magnet about at least 10cm or so away from the outside
container in all directions in the pane of the containers' openings (certainly
not coaxially!). The compass inside should be placed EXACTLY at the center
of both containers. This compass must be sitting half-way up the smaller
container, which in turn should be sitting halfway up the larger container.
The smaller container must be centered within the larger container. One
gets the BEST results when magnetically shielding the compass included
from the Earth's own magnetic field, rather than that of a closer, more
concentrated toy magnet. Also, in general, try keeping the included compass
away from any other toy magnets, as this compass can be easily magnetized/demagnetized
by them, which can destroy the compass' own, very weak, magnetic field,
and ruin its proper function. The results may be typically slight but still
easily noticeable and easily measureable, as these containers at best provide
only SOME protection. Proffessionals actually use extensively heavier and
more expensive magnetic shielding around a small room. Such proffessional
shielding will render the contained space inside it almost magnetically
neutral for almost all magnetic fields known.
A FEW WORDS OF CAUTION: You must remember that, for the
shielding to work well, the magnetic field to avoid must be OUTSIDE the
CONTAINER and NOT TOUCHING this container. These containers are very sensitive
to becoming magnetized themselves, either by PHYSICAL CONTACT in any way
with another magnetic object, or in the presence of an EXCESSIVELY STRONG
magnetic field or sufficiently string magnetic fields that are too close
to the containers. The container itself must NOT be magnetized AT ALL either.
This is "action-at-a-distance, part 5".
In the event that these containers DO become WEAKLY magnetized, there
are suggestions (included in the parts/materials list of the INTRODUCTION)
on how these containners could be demagnetized.