  We have been doing a sample survey in UBV photometry and proper motions as
part of an investigation of galactic structure and evolution. The programme is
based on Schmidt plates (from OCA, Tautenburg, Palomar and ESO Schmidt
telescopes) digitized with the MAMA machine (CAI, Paris). The high astrometric
quality of the MAMA gives access to micronic accuracy (leading to $<$ 2 mas per
year) on proper motions with a 35 years time base. The high proper motion
accuracy for faint star probes in wide-areas give access to the properties of
star samples out of the solar neighborhood. We have analyzed components of the
UVW galactic space motions resulting from the accurate proper motion surveys.
The kinematical distribution of F and G--type stars have been probed to
distances up to 2.5 kpc above the galactic plane. We have derived the constrain
on the structural parameters of the thin and thick disk components of the
Galaxy.
