_The Wave Wing of the Author._--If a similar cane has added to it, tapering rods of whalebone, which radiate in an outward direction to the extent of a foot or so, and the whalebones be covered by a thin sheet of india-rubber, an artificial wing, resembling the natural one in all its essential points, is at once produced (fig. 120). I propose to designate this wing, from the peculiarities of its movements, _the wave wing_ (fig. 121). If the wing referred to (fig. 121) be made to vibrate at its root, a series of longitudinal (_c d e_) and transverse (_f g h_) waves are at once produced; the one series running in the direction of _the length of the wing_, the other in the direction of _its breadth_ (_vide_ p. 148). This wing further _twists_ and _untwists_, figure-of-8 fashion, during the up and down strokes, as shown at fig. 122, p. 239 (compare with figs. 82 and 83, p. 158; fig. 86, p. 161; and fig. 103, p. 186). There is, moreover, a continuous play of the wing; the down stroke gliding into the up one, and _vice versâ_, which clearly shows that the down and up strokes are parts of one whole, and that neither is perfect without the other. [Illustration: FIG. 117. FIG. 117.--Represents a longitudinal section of bamboo cane ten feet long, and one inch wide.--_Original._] [Illustration: FIG. 118. FIG. 118.--The appearance presented by the same cane when made to vibrate by the hand. The cane vibrates on either side of a given line (_x x_), and appears as if it were in two places at the same time, viz., _c_ and _f_, _g_ and _d_, _e_ and _h_. It is thus during its vibration thrown into figures-of-8 or opposite curves.--_Original._] [Illustration: FIG. 119. FIG. 119.--The same cane when made to vibrate more rapidly. In this case the waves made by the cane are less in size, but more numerous. The cane is seen alternately on either side of the line _x x_, being now at _i_ now at _m_, now at _n_ now at _j_, now at _k_ now at _o_, now at _p_ now at _l_. The cane, when made to vibrate, has no dead points, a circumstance due to the fact that no two parts of it reverse or change their curves at precisely the same instant. This curious reciprocating motion enables the wing to seize and disengage itself from the air with astonishing rapidity.--_Original._] [Illustration: FIG. 120. FIG. 120.--The same cane with a flexible elastic curtain or fringe added to it. The curtain consists of tapering whalebone rods covered with a thin layer of india-rubber. _a b_ anterior margin of wing, _c d_ posterior ditto.--_Original._] [Illustration: FIG. 121.