The sub-division of the book into two volumes. Part I on Hydrostatics appeared alone in 1883 and in the preface a hope was expressed that Part II on Hydrodynamics would follow shortly. Several chapters were written and materials for other chapters were collected but laid aside owing to pressure of other work. In the matter of the sign of the velocity. A chapter on viscosity has been added as well as some applications of contour integration to problems of two- dimensional motion and some discussion of the part played by circulation in producing lift and of the application of conformal transformation to aerofoil theory. The chapter on viscosity is placed at the end of the book but it contains direct references to so few of the other chapters.