  We show that in general, the specification of a contact angle condition at
the contact line in inviscid fluid motions is incompatible with the classical
field equations and boundary conditions generally applicable to them. The
limited conditions under which such a specification is permissible are derived;
however, these include cases where the static meniscus is not flat. In view of
this situation, the status of the many `solutions' in the literature which
prescribe a contact angle in potential flows comes into question. We suggest
that these solutions which attempt to incorporate a phenomenological, but
incompatible, condition are in some, imprecise sense `weak-type solutions';
they satisfy or are likely to satisfy, at least in the limit, the governing
equations and boundary conditions everywhere except in the neighbourhood of the
contact line. We discuss the implications of the result for the analysis of
inviscid flows with free surfaces.
