DR PETTIGREW ON THE PHYSIOLOGY OF WINGS. 331 



the instrument and the medium on which it is destined to operate — the wing 

 acting in those very curves into which the atmosphere is naturally thrown in the 

 transmission of sound, in order, as appears to me, to secure the maximum of 

 progression with the minimum of slip. Can it be that the animate and inani- 

 mate world reciprocate, and that animal bodies are made to impress the inani- 

 mate in precisely the same manner as the inanimate impress each other f This 

 much seems certain : — The wind communicates to the water similar impulses to 

 those communicated to it by the fish in swimming ; and the wing in its vibrations 

 impinges upon the air as an ordinary sound would. The extremities of quad- 

 rupeds, moreover, describe spiral tracks on the land when walking and run- 

 ning ; so that one great law would seem to determine the course of the insect 

 in the air, the fish in the water, and the quadruped on the land." 



Various other passages might be adduced in elucidation and support of the 

 curve, wave, or figure of 8 theory of flying, as originally propounded by me, but 

 a sufficient number have, I trust, been cited to prove that the theory owes its 

 origin and development to no hasty generalisation from a few scattered and 

 imperfectly known facts, but that it rests upon a broad basis, such, in reality, as 

 nature herself supplies. 



In order that the reader may form his own conclusions on this point, I pro- 

 pose to lay before him in the course of my subsequent remarks the observations 

 and experiments on which the theory was originally founded. The present 

 memoir is illustrated by upwards of ninety original diagrams and drawings, the 

 intricacy of the subject being such as to necessitate a free use of the pencil. 

 The drawings have been made by myself from the life. I have gone into the 

 origin and development of the figure of 8 theory of flying somewhat in 

 detail ; first, because the passages selected have an obvious bearing on the 

 subject of the present communication ; and second, because nearly two 

 years after I had made my views known, Professor E. J. Marey (Col- 

 lege of France, Paris), published a series of lectures and papers in the 

 " Eevue des Cours Scientifiques de la France et de L'Etranger,"* and in 

 the " Comptes E-endus hebdomaclaires des Stances de L'Acade"mie des 

 Sciences," t in which the figure of 8 theory of wing movements is put 

 forth as a new discovery. Professor Marey made no allusion to my 

 researches, which was the more remarkable, as an abstract of my lecture, 

 already referred to (p. 322), as published in the Proceedings of the Royal 

 Institution of Great Britain in March 1867, was translated into French, and 



* Les mouvements de l'aile chez les insectes, p. 171, 13th Eevrier 1869. Mecanisnie du vol chez 

 les insectes — comment se fait la propulsion, p. 252, 20th Mars 1869. Du vol des oiseaux, p. 578, 

 14 Aout 1869. Du vol des oiseaux (suite), p. 601, 21 Aout 1869. Du vol des oiseaux (suite), p. 

 646, 11 Septembre 1869. Du vol des oiseaux (fin), p. 700, 2 October 1869. 



\ Determination experimental du mouvement des ailes des insectes pendant le vol. Par 

 M. E. J. Marey. Tome LXVII. p. 1341, Tome LXVIII. p. 667. 



