[25] Progress in Flying Machines, Chanute.
[26] The air rises with increased temperature, hence with increased volume displacement, thus causing the wind in general to have a slightly ascending trend.
[27] Aëronautical Annual, 1897.
[28] Ella Tidswell, The Aëronautical Journal, July, 1909.
[29] W. J. S. Lockyer, Nature, August 12, 1897.
[30] Wenham used superposed planes, Stringfellow superposed planes trussed by vertical rods and diagonal wires, Phillips, Lilienthal and Hargrave superposed arched surfaces.
[31] See Aëronautic Annual, 1896.
[32] Aërial Warfare, Hearne, p. 77.
[33] Published by the American Engineer and Railway Journal.
[34] This kind of automatic stability may be called inherent stability.