  High resolution spectra data of red clump stars towards the NGP have been
obtained with the high resolution spectrograph Elodie at OHP for Tycho-2
selected stars. Combined with Hipparcos local analogues, we determine both the
gravitational force law perpendicaular to the Galactic plane, and the total
surface mass density and thickness of the Galactic disk. The surface mass
density of the Galactic disk within 800 pc derived from this analysis is
Sigma(|z|<800pc)=76 Msol.pc-2 and, removing the dark halo contribution, the
total disk mass density is Sigma0=67 Msol.pc-2 at solar radius. The thickness
of the total disk mass distribution is dynamicaly measured for the first time
and is found to be 390pc in relative agreement with the old stellar disk scale
height. All dynamical evidences concerning the structure of the disk (its local
volume density -i.e. the Oort limit-, its surface density and its thickness)
are compatible with our knowledge of the corresponding stellar disk properties.
