  We study the linking numbers in a rational homology 3-sphere and in the
infinite cyclic cover of the complement of a knot. They take values in $\Bbb Q$
and in ${Q}({\Bbb Z}[t,t^{-1}])$ respectively, where ${Q}({\Bbb Z}[t,t^{-1}])$
denotes the quotient field of ${\Bbb Z}[t,t^{-1}]$. It is known that the
modulo-$\Bbb Z$ linking number in the rational homology 3-sphere is determined
by the linking matrix of the framed link and that the modulo-${\Bbb
Z}[t,t^{-1}]$ linking number in the infinite cyclic cover of the complement of
a knot is determined by the Seifert matrix of the knot. We eliminate ` modulo
$\Bbb Z$' and ` modulo ${\Bbb Z}[t,t^{-1}]$'. When the finite cyclic cover of
the 3-sphere branched over a knot is a rational homology 3-sphere, the linking
number of a pair in the preimage of a link in the 3-sphere is determined by the
Goeritz/Seifert matrix of the knot.
