332 DR PETTIGREW ON THE PHYSIOLOGY OF WINGS. 



appeared on the 21st of September of that year in the same Journal"' in which 

 Professor Marey's lectures were originally published. Having had my attention 

 directed to this circumstance, I addressed a letter to the French Academy on 

 the 28th of March 1870, which appeared in the " Comptes Eendus " (p. 875) on 

 the 18th of April 1870. In it I claim to have been the first to describe and 

 illustrate the following points, viz : — 



That quadrupeds walk, and fishes swim, and insects, bats, and birds fly by 



figure of 8 movements. 

 That the flipper of the sea bear, the swimming wing of the penguin, and 

 the wing of the insect, bat, and bird, are screws structurally, and 

 resemble the blade of an ordinary screw propellor. 

 That those organs are screws functionally, from their twisting and un- 

 twisting, and from their rotating in the direction of their length, 

 when they are made to oscillate. 

 That they have a reciprocating action, and reverse their planes more or less 



completely at every stroke. 

 That the wing describes a figure of 8 track in space when the flying animal 



is artificially fixed. 

 That the wing, when the flying animal is progressing at a high speed in a 

 horizontal direction, describes a looped and then a ivaved track, from 

 the fact that the figure of 8 is gradually opened out or unravelled as the 

 animal advances. 

 That the wing acts after the manner of a kite. 



Previous to replying to the foregoing, Professor Marey wrote me, to inquire 

 how he could respond to my "juste reclamation," without entering into a dis- 

 cussion which Avould needlessly complicate the question. I thereupon asked 

 him to admit in a letter addressed to the French Academy my claim to have 

 described and illustrated before him the figure of 8 movements made by the 

 wings of insects, bats, and birds, when those animals are artificially fixed, and 

 of the spiral and undulatory wave tracks made by the wings of said insects, 

 bats, and birds, when the animals are flying at a high horizontal speed. This 

 he has done, as the subjoined extract from his letter, printed in the " Comptes 

 Rendus " for May 16, 1870 (p. 1093), will show :— " J'ai constate" qu' effective- 

 ment M. Pettigrew a vu avant moi, et repr^sente" dans son M^moire, la forme 

 en 8 du parcours, de l'aile de l'insecte: que la methode optique a laquelle j'avais 

 recours est a peu pres identique a la sienne . . . . je m' empresse de 

 satisfaire a cette demande legitime, et je laisse entierement la priorite sur moi, 

 a M. Pettigrew relativement a la question ainsi restreinte." 



Mode of Investigation pursued by the Author. — I obtained my results by 



* Revue des Cours Scientifiques de la France et de l'Etranger. 



