Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/124

§ 79 extent relatively to the “enclosure,” i.e., the fluid at infinity, and relatively to the body itself. In the present work the former are referred to as the lines of flow and the latter as the stream lines, the latter term being employed in all cases where the primary flow is superposed on a motion of translation. This is merely a matter of convenience in terminology, in which the present work differs from some of the standard text-books in which the term stream line is used more generally.

Of particular interest to the present subject (as will be hereafter demonstrated) is the case of cyclic motion superposed on a motion of translation. Fig. 48 gives the plotting in this