The dynamics of bodies containing fluids is a subject of long-standing im­ portance in many technical applications. The stability of motion of such bodies, in particular, has been the subject of study by Soviet engineers and applied mathematicians who have brought their fuH powers of analysis to bear on the problem, and have succeeded in developing a very weH-founded body of theory. It is difficult to find a more striking example anywhere of the application of the classical methods of analytical mechanics, together with more modern concepts of stability analysis, in such a comprehensive and elegent form as that presented by Profs. Moiseyev and Rumyantsev. Therefore, it is highly significant that this recent monograph has been trans­ lated and made available to the English-speaking community. H. NORMAN ABRAMSON San Antonio July, 1967 v Foreword During the last 15-20 years, problems of dynamics of rigid bodies with fluid-filled cavities have increasingly attracted the attention of scientists.