The string method is an efficent numerical method for finding transition
paths and transition rates in metastable systems. The dynamics of the
string are governed by a Hamilton-Jacobi type of equation. We construct
a stable and high order numerical scheme to estimate the first order
spatial derivatives, or the tangent vectors in the equation. The
construction is based on the idea of the upwind scheme and the essentially
nonoscillatory scheme (ENO). Numerical examples demonstrate the improvement
of the accuracy by the new scheme.