Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/160

§ 107 The wing section given in Fig. 57 is that of a herring gull (Larus argentatus). The dotted line gives the form as plotted from templates made shortly after the bird had been killed; the full line gives the approximate form in flight when sustaining the weight of the bird. The direction of flight is supposed horizontal.

§ 108. Historical.—Historically, so far as the author has been able to ascertain, the credit of the discovery of the dipping edge is due to Horatio Frederick Phillips, whose publication is to be found in the specification of Patent 13,768 of 1884. The discovery appears to have been made as a matter of practical experience, and, as often takes place under these circumstances, the theory given by the inventor in his specification is erroneous. Just, however, as in patent law an inventor's theory, however unsound, is not held to invalidate an invention, so in the matter of discovery, the fact that a discoverer does not fully understand the fact that he has been the first to ascertain, does not in any way detract from the credit due. In a case such as the present the fact that the discovery is based on practical experience in the face of an imperfect and in reality hostile theory adds rather than otherwise to its value.

Fig. 58 is a reproduction of the forms of wing section given (as applied to artificial flight) in the specification cited. The motion