  The swept-field experiments on magnetic molecular solids such as \Fe8 are
studied using Monte Carlo simulations. A kinetic equation is developed to
understand the phenomenon. It is found that the simulations provide a
quantitatively accurate account of the experiments. The kinetic equation
provides a similarly accurate account except at very low sweep velocities,
where it fails modestly. This failure is due to the neglect of short-range
correlations between the dipolar magnetic fields seen by the molecular spins.
Both the simulations and the kinetic equation provide a good understanding of
the distribution of these dipolar fields.
