  In this paper, we aim to estimate the vertical gradients in the rotational
velocity of the Galaxy. This is carried out in the framework of a global thin
disc model approximation. The predicted gradient values coincide with the
observed vertical fall-off in the rotation curve of the Galaxy. The gradient is
estimated based on a statistical analysis of trajectories of test bodies in the
gravitational field of the disc and in an analytical way using a quasi-circular
orbit approximation. The agreement of the results with the gradient
measurements is remarkable in view of other more complicated, non-gravitational
mechanisms used for explaining the observed gradient values. Finally, we find
that models with a significant spheroidal component give worse vertical
gradient estimates than the simple disc model. In view of these results, we can
surmise that, apart from the central spherical bulge and Galactic halo, the
gross mass distribution in the Galaxy forms a flattened rather than spheroidal
figure.
