PREFACE. 



THE following attempt to set forth in a systematic and con 

 nected form the present state of the theory of the Motion of 

 Fluids, had its origin in a course of lectures delivered in Trinity 

 College, Cambridge, in 1874, when the need for a treatise on the 

 subject was strongly impressed on my mind. Various circumstances 

 have retarded the completion of the work in a form fit for the 

 press ; but as the delay has enabled me to incorporate the results 

 of several important recent investigations, and altogether to render 

 the volume less inadequate to its purpose than it would otherwise 

 have been, this is hardly matter for regret. 



I have endeavoured, throughout the book, to attribute to their 

 proper authors the various steps in the development of the subject. 

 The list of Memoirs and Treatises at the end of the book has no 

 pretensions to completeness, and as it is to a great extent based on 



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