  Inspired by recent experiments by Geim et al. we discuss the classical theory
of the Hall effect of a 2 dimensional electron gas in an inhomogeneous magnetic
field. The field modulation is in the form of flux tubes created by a
superconductor overlayer. We find that an approach, where the vortices are
treated as individual scatterers contributing to the collision term in the
Boltzman equation will not work --- it leads to a vanishing Hall constant at
$T=0$. If the field is treated as a smooth contribution to the driving term in
the Boltzman equation, the classical Hall constant emerges, in agreement with
experiments when the Fermi wavelength is short in comparison with all other
lengths in the problem.
