  The relation between the Wiener index $W(G)$ and the eccentricity
$\varepsilon(G)$ of a graph $G$ is studied. Lower and upper bounds on $W(G)$ in
terms of $\varepsilon(G)$ are proved and extremal graphs characterized. A
Nordhaus-Gaddum type result on $W(G)$ involving $\varepsilon(G)$ is given. A
sharp upper bound on the Wiener index of a tree in terms of its eccentricity is
proved. It is shown that in the class of trees of the same order, the
difference $W(T) - \varepsilon(T)$ is minimized on caterpillars. An exact
formula for $W(T) - \varepsilon(T)$ in terms of the radius of a tree $T$ is
obtained. A lower bound on the eccentricity of a tree in terms of its radius is
also given. Two conjectures are proposed. The first asserts that the difference
$W(G) - \varepsilon(G)$ does not increase after contracting an edge of $G$. The
second conjecture asserts that the difference between the Wiener index of a
graph and its eccentricity is largest on paths.
