Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/161

Rh is supposed to take place from left to right, as in Fig. 57. Fig. 59 illustrates a modified form given in a further specification by the same inventor, 13,311 of 1891. These two figures show clearly the nature of the feature under discussion. In both specifications the theory given is inadequate.

The advantages of the arched form of wing section were known to the late Herr Lilienthal at the time of his experiments in flight, 1890–94, and the discovery has been attributed to him by some writers. It is possible that Lilienthal was unaware of Phillips' previous work, and that discovery by him was made independently. There is no evidence to show that Lilienthal possessed more than a practical acquaintance with the arched form.