et from a philosophical instrument maker, you will see a mark on
one of its ends. Supposing, then, that you drew your needle along the
end thus marked, and that the point of your needle was the last to
quit the magnet, you will find that the point turns to the south, the
eye of the needle turning towards the north. Make sure of this, and
do not take the statement on my authority.

Now take a second darning-needle like the first, and magnetise it in
precisely the same manner: freely suspended it also will turn its eye
to the north and its point to the south. Your next step is to examine
the action of the two needles which you have thus magnetised upon each
other.

Take one of them in your hand, and leave the other suspended; bring
the eye-end of the former near the eye-end of the latter; the
suspended needle retreats: it is repelled. Make the same experiment
with the two points; you obtain the same result, the suspended needle
is repelled. Now cause the dissimilar ends to act on each other--you
have attraction--point attracts eye, and eye attracts point. Prove
the reciprocity of this action by removing the suspended needle, and
putting the other in its place. You obtain the same result. The
attraction, then, is mutual, and the repulsion U mutual. You have
thus demonstrated in the clearest manner the fundamental law of
magnetism, that like poles repel, and that unlike poles attract, each
other. You may say that this is all easily understood without doing;
but _do it_, and your knowledge will not be confined to what I have
uttered here.

I have said that one end of your bar magnet has a mark upon it; lay
several silk fibres together, so as to get sufficient strength, or
employ a thin silk ribbon, and form a loop large enough to hold your
magnet. Suspend it; it turns its marked end towards the north. This
marked end is that which in England is called the north pole. If a
common smith has made your magnet, it will be convenient to determine
its north pole yourself, and to mark it with a file. Vary your
experiments by causing your magnetised darning-needle to attract and
repel your large magnet; it is quite competent to do so. In
magnetising the needle, I have supposed the point to be the last to
quit the marked end of the magnet; the point of the needle is a south
pole. The end which last quits the magnet is always opposed in
polarity to the end of the magnet with which it, has been last in
contact.

Yo