<pre>
Take the two bars, and put them together like a T, so that one bisects the
other.

<pre>
         +-------------------+
 bar A ->||                   ||
         +-------------------+
                  +--+
                  ||  ||
                  ||  ||
                  ||  ||
 bar B ---------->||  ||
                  ||  ||
                  ||  ||
                  ||  ||
                  ||  ||
                  +--+
</pre>

If they stick together, then bar B is the magnet.  If they don't, bar A is
the magnet. (reasoning follows)

Bar magnets are "dead" in their centers (i.e., there is no magnetic force,
since the two poles cancel out).  So, if bar A is the magnet, then bar B
won't stick to its center.

However, bar magnets are quite "alive" at their edges (i.e., the magnetic
force is concentrated).  So, if bar B is the magnet, then bar A will stick
nicely to its end.
</pre>
