  Flattened liquid drops poured on a very hot surface evaporate quite slowly
and float on a film of their own vapour. In the cavities of a surface, an
unusual type of vibrational motions occurs. Large vibrations take place and
different forms of dynamic drops are possible. They form elliptic patterns with
two lobes or hypotrochoid patterns with three lobes or more. The lobes are
turning relatively to the hot surface. We present a model of vibrating motions
of the drops. Frequencies of the vibrations are calculated regarding the number
of lobes. The computations agree with experiments.
