  In view of Ehlers-Pirani-Schild formalism, since 1972 Weyl geometries should
be considered to be the most appropriate and complete framework to represent
(relativistic) gravitational fields. We shall here show that in any given
Lorentzian spacetime (M,g) that admits global timelike vector fields any such
vector field u determines an essentially unique Weyl geometry ([g], \Gamma)
such that u is \Gamma-geodesic (i.e. parallel with respect to \Gamma).
