In establishing conditions for
continuity of the height of a capillary surface at a re-entrant corner point of
the domain of definition, Lancaster and Siegel introduced a hypothesis of symmetry,
which does not appear in corresponding conditions for a protruding corner. We show
here that the hypothesis cannot be discarded. Starting with a symmetric
configuration for which the surface height is continuous at the corner point in
accordance with the hypotheses of those authors, we show that the height can be
made discontinuous by an asymmetric domain perturbation that is in an asymptotic
sense arbitrarily small, and for which all hypotheses other than that of symmetry
remain in force.