  Tabe and Yokoyama found recently that the optical axis in a chiral monolayer
of a ferronematic rotates when water evaporates from the bath: the chiral
molecules act as propellers. When the axis is blocked at the lateral walls of
the trough, the accumulated rotation inside creates huge splays and bends. We
discuss the relaxation of these tensions, assuming that a single dust particle
nucleates disclination pairs. For the simplest geometry, we then predict a long
delay time followed by a non-periodic sequence of ``bursts''. These ideas are
checked by numerical simulations.
