| Abstract: | We compare theW velocity dispersions of Brosche, Schwan & Schwarz (2001) with more recent results. The increase with the distance |z | from the galactic plane is confirmed, although perhaps with reduced amplitude. This could be interpreted either as one homogenous population or as a superposition of (at least) two populations with two constant dispersions and two scale heights. For each of the possibilities we propose a simple model. Combined with two observational variants for the velocity variation, we obtain surface densities up to |z | = 250 pc ranging from 5 to 44 M⊙ pc–2. Thus the case for considerable dark matter in the neighbourhood of the galactic plane is not supported |
