^{page 336 note *} Vide “The Various Modes of Flight in Relation to Aëronautics;” by the Author in the “Proceedings of the Royal Institution of Great Britain for March 22, 1867;” also his memoir “On the Mechanical Appliances by which Flight is attained in the Animal Kingdom,” read to the Linnean Society of London on the 6th and 20th of June 1867, and published in extenso in the 26th volume of their Transactions, a large number of woodcuts and engravings being specially devoted to the elucidation of the figure-of-8 wave track made by the wing as observed in the flight of the insect, bat, and bird.

^{page 336 note †} “Revue des Cours Scientifiques de la France et de l'Etranger.” Professor Marey, in a letter addressed to the French Academy, under date May 16, 1870, fully acknowledges the author's claim to priority (as regards himself) in the discovery of the figure-of-8 wave movements made by the wing in flying. M. Marey, in the letter referred to, states (“Comptes Rendus,” page 1093, May 16, 1870), “J'ai constaté qu' effectivement M. Pettigrew a vu avant moi, et représenté dans son Mémoire, la forme en 8 du parcours de l'aile de l'insecte: que la méthode optique à laquelle j'avais recours est à peu près identique à la sienne… je m' empresse de satisfaire à cette demande légitime, et je laisse entièrement la priorité sur moi, à M. Pettigrew relativement à la question ainsi restreinte.”

^{page 337 note *} Revue des Cours Scientifiques de la France et de l'Etranger, p. 252. 20th March 1869.

^{page 337 note †} The wings of the beetles are jointed, so that they can be folded up beneath the elytra or wing cases.

^{page 345 note *} Borelli (1668), Durkheim, and Marey state that an artificial wing should be composed of a rigid rod in front and a flexible sail behind, but experiment has convinced the author that no part of the wing should be absolutely rigid.

^{page 347 note *} The author has made a great variety of artificial wings. Of these some are in one piece, with a continuous covering; others in a single piece, with the cover broken up into a large number of small valves; others in several pieces, with a continuous covering, and others jointed, with the cover broken up into a number of valvular segments. In all cases the frames of the wings are composed of elastic material, such as steel tubes, bamboo and other canes, osier twigs, whalebone, gutta percha, &c., &c.; the covers of the wings are made of india-rubber cloth, tracing cloth, argentine, linen, silk, &c., &c.; the springs of the wings of steel, caoutchouc, &c., &c.