  We present the first comparisons of a newly developed Galactic Structure and
Kinematic Model to magnitude and color counts, as well as relative proper
motions, in the fields of the open clusters NGC 188 [(l, b)= (122.8 deg, +22.4
deg)] and NGC 3680 [(l,b)= (286.8 deg, +16.9 deg)]. In addition to determining
the reddening toward these two clusters, it is shown that starcounts at
intermediate Galactic latitudes in the range 11< V< 17 allow us to constrain
the model scale-height for disk subgiants. We obtain a mean value of 250 +/- 32
pc, in agreement with previous determinations of the scale-height for
red-giants. We are also able to constrain the scale-height of main-sequence
stars, and the distance of the sun from the Galactic plane, ruling out the
possibility of a value of +40 pc, in favor of a smaller value. Comparisons with
the observed proper-motion histograms indicate that the velocity dispersion of
disk main-sequence stars must increase with distance from the Galactic plane in
order to match the observed proper-motion dispersion. The required increase is
consistent with the values predicted by dynamical models, and provides a clear
observational evidence in favor of such gradients. The shape of the observed
proper-motion distribution is well fitted within the Poisson uncertainties.
This implies that corrections to absolute proper motion (and, therefore, space
velocities) for open clusters may be obtained using our model when no inertial
reference frame is available. Using this approach, the derived tangential
motions for NGC 188 and NGC 3680 are presented.
