  In this paper we suppose G is a finite group acting tamely on a regular
projective curve X over Z and V is an orthogonal representation of G of
dimension 0 and trivial determinant. Our main result determines the sign of the
$\epsilon$-constant $\epsilon(X/G,V)$ in terms of data associated to the
archimedean place and to the crossing points of irreducible components of
finite fibers of X, subject to certain standard hypotheses about these fibers.
